JP2021076178A - Power transmission device - Google Patents

Power transmission device Download PDF

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Publication number
JP2021076178A
JP2021076178A JP2019202770A JP2019202770A JP2021076178A JP 2021076178 A JP2021076178 A JP 2021076178A JP 2019202770 A JP2019202770 A JP 2019202770A JP 2019202770 A JP2019202770 A JP 2019202770A JP 2021076178 A JP2021076178 A JP 2021076178A
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JP
Japan
Prior art keywords
bearing
nut
driven pulley
power transmission
transmission device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2019202770A
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Japanese (ja)
Inventor
佑太 千原
Yuta CHIHARA
佑太 千原
迫田　裕成
Hiroshige Sakota
裕成 迫田
拓弥 三輪
Takuya Miwa
拓弥 三輪
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NSK Ltd
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NSK Ltd
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Filing date
Publication date
Application filed by NSK Ltd filed Critical NSK Ltd
Priority to JP2019202770A priority Critical patent/JP2021076178A/en
Priority to EP20884832.5A priority patent/EP4056866A4/en
Priority to CN202080075351.2A priority patent/CN114641632A/en
Priority to US17/774,629 priority patent/US20220371651A1/en
Priority to PCT/JP2020/039785 priority patent/WO2021090696A1/en
Priority to KR1020227015159A priority patent/KR20220079912A/en
Publication of JP2021076178A publication Critical patent/JP2021076178A/en
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0442—Conversion of rotational into longitudinal movement
    • B62D5/0445—Screw drives
    • B62D5/0448—Ball nuts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C27/00—Elastic or yielding bearings or bearing supports, for exclusively rotary movement
    • F16C27/06—Elastic or yielding bearings or bearing supports, for exclusively rotary movement by means of parts of rubber or like materials
    • F16C27/066—Ball or roller bearings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0403—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by constructional features, e.g. common housing for motor and gear box
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0421—Electric motor acting on or near steering gear
    • B62D5/0424—Electric motor acting on or near steering gear the axes of motor and final driven element of steering gear, e.g. rack, being parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
    • F16C19/16—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with a single row of balls
    • F16C19/163—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with a single row of balls with angular contact
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/36—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/54—Systems consisting of a plurality of bearings with rolling friction
    • F16C19/546—Systems with spaced apart rolling bearings including at least one angular contact bearing
    • F16C19/547—Systems with spaced apart rolling bearings including at least one angular contact bearing with two angular contact rolling bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C25/00—Bearings for exclusively rotary movement adjustable for wear or play
    • F16C25/06—Ball or roller bearings
    • F16C25/08—Ball or roller bearings self-adjusting
    • F16C25/083—Ball or roller bearings self-adjusting with resilient means acting axially on a race ring to preload the bearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/581—Raceways; Race rings integral with other parts, e.g. with housings or machine elements such as shafts or gear wheels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C35/00—Rigid support of bearing units; Housings, e.g. caps, covers
    • F16C35/08—Rigid support of bearing units; Housings, e.g. caps, covers for spindles
    • F16C35/12—Rigid support of bearing units; Housings, e.g. caps, covers for spindles with ball or roller bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
    • F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H25/24—Elements essential to such mechanisms, e.g. screws, nuts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2229/00—Setting preload
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2326/00—Articles relating to transporting
    • F16C2326/20—Land vehicles
    • F16C2326/24—Steering systems, e.g. steering rods or columns
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2361/00—Apparatus or articles in engineering in general
    • F16C2361/63—Gears with belts and pulleys
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2380/00—Electrical apparatus
    • F16C2380/26—Dynamo-electric machines or combinations therewith, e.g. electro-motors and generators
    • F16C2380/27—Motor coupled with a gear, e.g. worm gears
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/66—Special parts or details in view of lubrication
    • F16C33/6603—Special parts or details in view of lubrication with grease as lubricant
    • F16C33/6607—Retaining the grease in or near the bearing
    • F16C33/6614—Retaining the grease in or near the bearing in recesses or cavities provided in retainers, races or rolling elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H2025/2031—Actuator casings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H2025/2062—Arrangements for driving the actuator
    • F16H2025/2081—Parallel arrangement of drive motor to screw axis
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • F16H2025/2062—Arrangements for driving the actuator
    • F16H2025/2096—Arrangements for driving the actuator using endless flexible members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/32—Friction members
    • F16H55/36—Pulleys
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/32—Friction members
    • F16H55/36—Pulleys
    • F16H55/48—Pulleys manufactured exclusively or in part of non-metallic material, e.g. plastics
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating
    • F16H57/0463—Grease lubrication; Drop-feed lubrication
    • F16H57/0464—Grease lubrication
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating
    • F16H57/0467—Elements of gearings to be lubricated, cooled or heated
    • F16H57/0469—Bearings or seals
    • F16H57/0471—Bearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating
    • F16H57/048—Type of gearings to be lubricated, cooled or heated
    • F16H57/0497—Screw mechanisms

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Power Steering Mechanism (AREA)
  • Transmission Devices (AREA)
  • Rolling Contact Bearings (AREA)
  • Support Of The Bearing (AREA)
  • Pulleys (AREA)

Abstract

To provide a power transmission device capable of reducing rigidity to a moment load of a bearing.SOLUTION: A power transmission device includes: a housing; a ball screw device having a nut, a screw shaft, and a plurality of balls; a pulley device having a driving pulley to which power is transmitted from a power source to drive, a driven pulley fixed to the nut, and a belt wound on outer peripheral faces of the driving pulley and the driven pulley; a first bearing and a second bearing disposed between the housing and the nut and arranged in a center axis direction in parallel with a center axis of the nut; and a preload application member for applying a preload to the first bearing and the second bearing. The first bearing and the second bearing are disposed in face-to-face combination, and respectively disposed at both sides of the driven pulley, each of the first bearing and the second bearing includes an outer ring fitted to the housing, and the outer ring is pressed toward the driven pulley by the preload application member, and forms a clearance with respect to the driven pulley while separating from the driven pulley.SELECTED DRAWING: Figure 4

Description

本発明は、動力伝達装置に関する。 The present invention relates to a power transmission device.

電動パワーステアリング装置の種類として、ラックアシスト式の電動パワーステアリング装置が挙げられる。特許文献１のラックアシスト式の電動パワーステアリング装置は、電動モータの動力をラックに伝達するため、動力伝達装置を備える。特許文献１の動力伝達装置は、ボールねじ装置と、プーリ装置と、複列の軸受と、を備える。ボールねじ装置は、ラックと一体に形成されたねじ軸と、複列の軸受に支持されるナットと、ねじ軸の第１溝とナットの第２溝との間に配置された複数のボールと、を備える。また、プーリ装置は、動力源である電動モータの出力軸に固定される駆動プーリと、ナットの外周に嵌合する従動プーリと、駆動プーリと従動プーリの外周面に巻き掛けられるベルトと、を備える。 Examples of the type of electric power steering device include a rack-assisted electric power steering device. The rack-assisted electric power steering device of Patent Document 1 includes a power transmission device for transmitting the power of the electric motor to the rack. The power transmission device of Patent Document 1 includes a ball screw device, a pulley device, and a double-row bearing. The ball screw device includes a screw shaft integrally formed with a rack, a nut supported by a double-row bearing, and a plurality of balls arranged between a first groove of the screw shaft and a second groove of the nut. , Equipped with. Further, the pulley device includes a drive pulley fixed to the output shaft of the electric motor which is a power source, a driven pulley fitted to the outer circumference of the nut, and a belt wound around the drive pulley and the outer peripheral surface of the driven pulley. Be prepared.

特開２０１８−７０１１７号公報Japanese Unexamined Patent Publication No. 2018-70117

特許文献１の軸受は、作用点間距離が大きい背面組合せとなっており、モーメント荷重に対する剛性が高い。つまり、反作用としてボールねじ装置に入力されるモーメント荷重も大きい。ボールねじ装置は、アキシアル荷重に特化した部品であり、大きなモーメント荷重が入力されると、異音が発生する可能性があり、望ましくない。よって、軸受のモーメント荷重に対する剛性を低減させて、ボールねじ装置に入力されるモーメント荷重を低減させることが望まれている。 The bearing of Patent Document 1 has a back surface combination in which the distance between working points is large, and has high rigidity against a moment load. That is, the moment load input to the ball screw device as a reaction is also large. The ball screw device is a component specialized for an axial load, and when a large moment load is input, abnormal noise may be generated, which is not desirable. Therefore, it is desired to reduce the rigidity of the bearing with respect to the moment load and reduce the moment load input to the ball screw device.

本開示は、上記の課題に鑑みてなされたものであって、軸受のモーメント荷重に対する剛性を低減させることができる動力伝達装置を提供することを目的とする。 The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a power transmission device capable of reducing the rigidity of a bearing with respect to a moment load.

上記の目的を達成するため、本開示の一態様に係る動力伝達装置は、ハウジングと、前記ハウジングに収容されるナット、前記ナットを貫通するねじ軸、及び前記ナットと前記ねじ軸との間に配置される複数のボールを有するボールねじ装置と、動力源から動力が伝達されて駆動する駆動プーリ、前記ナットに固定される従動プーリ、及び駆動プーリと前記従動プーリの外周面に巻き掛けられるベルトを有するプーリ装置と、前記ハウジングと前記ナットとの間に設けられ、前記ナットの中心軸に平行な中心軸方向に並ぶ第１軸受及び第２軸受と、前記第１軸受及び前記第２軸受に予圧を与える予圧付与部材と、を備え、前記第１軸受及び前記第２軸受は、正面組合せに配置されるとともに、前記従動プーリの両側にそれぞれ配置され、前記第１軸受及び前記第２軸受のそれぞれは、前記ハウジングに嵌め合わされる外輪を含み、前記外輪は、前記予圧付与部材によって前記従動プーリに向かって押圧されるとともに、前記従動プーリと離隔して前記従動プーリとの間に隙間が形成されている。 In order to achieve the above object, the power transmission device according to one aspect of the present disclosure is provided between a housing, a nut housed in the housing, a screw shaft penetrating the nut, and between the nut and the screw shaft. A ball screw device having a plurality of balls to be arranged, a drive pulley driven by transmitting power from a power source, a driven pulley fixed to the nut, and a belt wound around the drive pulley and the outer peripheral surface of the driven pulley. The first bearing and the second bearing provided between the housing and the nut and arranged in the direction of the central axis parallel to the central axis of the nut, and the first bearing and the second bearing. A preload applying member for applying preload is provided, and the first bearing and the second bearing are arranged in a front combination and are arranged on both sides of the driven pulley, respectively, of the first bearing and the second bearing. Each includes an outer ring that is fitted into the housing, and the outer ring is pressed toward the driven pulley by the preload applying member and is separated from the driven pulley to form a gap between the outer ring and the driven pulley. Has been done.

第１軸受及び第２軸受は、作用点間距離が小さい正面組合せとなっている。つまり、第１軸受及び第２軸受によるモーメント荷重に対する剛性が低い。よって、ボールねじ装置に入力されるモーメント荷重が低減し、異音の発生が抑制される。また、上記構成によれば、外輪に中心軸方向の寸法誤差があると、この寸法誤差は従動プーリとの隙間に入り込んで寸法誤差が吸収される。よって、外輪は中心軸方向に変位せず、転動体に作用する荷重は、予圧付与部材の押圧による荷重のみとなる。この結果、所定の予圧量となり、軸受トルクの安定化を図れる。 The first bearing and the second bearing have a frontal combination in which the distance between the working points is small. That is, the rigidity against the moment load by the first bearing and the second bearing is low. Therefore, the moment load input to the ball screw device is reduced, and the generation of abnormal noise is suppressed. Further, according to the above configuration, if the outer ring has a dimensional error in the central axis direction, this dimensional error enters the gap with the driven pulley and the dimensional error is absorbed. Therefore, the outer ring is not displaced in the central axis direction, and the load acting on the rolling element is only the load due to the pressing of the preload applying member. As a result, a predetermined preload amount is obtained, and the bearing torque can be stabilized.

一態様に係る動力伝達装置の望ましい態様として、前記第１軸受の接触角の延長線と前記ナットの中心軸とが交わる第１交点と、前記第２軸受の接触角の延長線と前記ナットの中心軸とが交わる第２交点と、は前記ナットの中心軸上で一致し、前記従動プーリの外周面の前記中心軸方向の中央を通り、かつ前記ナットの中心軸と直交する仮想線は、前記第１交点と前記第２交点の両方を通る。これにより、第１軸受及び第２軸受は、第１交点と第２交点とが一致する１点で実質ボールねじ装置を支持する。よって、モーメント荷重に対する剛性が低い。また、第１軸受及び第２軸受の支点とベルトの張力の力点とが一致し、ナットには、モーメント荷重が発生しない。 As a desirable aspect of the power transmission device according to one aspect, the first intersection where the extension line of the contact angle of the first bearing and the central axis of the nut intersect, the extension line of the contact angle of the second bearing, and the nut. The second intersection where the central axis intersects is a virtual line that coincides on the central axis of the nut, passes through the center of the outer peripheral surface of the driven pulley in the central axis direction, and is orthogonal to the central axis of the nut. It passes through both the first intersection and the second intersection. As a result, the first bearing and the second bearing support the substantially ball screw device at one point where the first intersection and the second intersection coincide with each other. Therefore, the rigidity against the moment load is low. Further, the fulcrums of the first bearing and the second bearing coincide with the force points of the tension of the belt, and no moment load is generated on the nut.

一態様に係る動力伝達装置の望ましい態様として、前記ナットの外周面には、硬化処理されて転動体が転動する内輪軌道面が２つ形成されている。これにより、内輪が不要となり、動力伝達装置を径方向に小型化することができる。また、ベルトの振動により従動プーリが中心軸方向に移動するような荷重を受けて従動プーリが隣接する内輪を押圧しても、内輪は軸方向に変位しない。よって、内輪が転動体を押圧する押圧量は増加せず、軸受トルクの増大が回避される。 As a desirable aspect of the power transmission device according to one aspect, two inner ring raceway surfaces that are hardened and the rolling element rolls are formed on the outer peripheral surface of the nut. As a result, the inner ring becomes unnecessary, and the power transmission device can be miniaturized in the radial direction. Further, even if the driven pulley presses the adjacent inner ring under a load such that the driven pulley moves in the central axial direction due to the vibration of the belt, the inner ring does not displace in the axial direction. Therefore, the amount of pressure that the inner ring presses against the rolling element does not increase, and an increase in bearing torque is avoided.

一態様に係る動力伝達装置の望ましい態様として、前記ナットの外周面には、径方向内側に窪む溝部が形成され、前記従動プーリは、樹脂製であり、インサート成型により前記ナットと一体化され、前記従動プーリは、一部が前記溝部に入り込んでいる。これにより、従動プーリは、ナットに対して周方向に位置ずれし難く、回転運動を確実にナットに伝達することができる。また、従動プーリは、ナットに対して中心軸方向に位置ずれし難い。これにより、従動プーリは、ベルトから中心軸方向に移動するような荷重を受けたとしても、移動しない。従って、受動プーリが内輪や外輪を押圧する、ということが防止され、軸受に付与される予圧量を所定量に維持することができる。 As a desirable aspect of the power transmission device according to one aspect, a groove portion recessed inward in the radial direction is formed on the outer peripheral surface of the nut, the driven pulley is made of resin, and is integrated with the nut by insert molding. , The driven pulley is partially inserted into the groove. As a result, the driven pulley is unlikely to be displaced in the circumferential direction with respect to the nut, and the rotational motion can be reliably transmitted to the nut. Further, the driven pulley is unlikely to be displaced in the central axis direction with respect to the nut. As a result, the driven pulley does not move even if it receives a load that moves from the belt in the central axis direction. Therefore, it is possible to prevent the passive pulley from pressing the inner ring and the outer ring, and to maintain the preload applied to the bearing at a predetermined amount.

一態様に係る動力伝達装置の望ましい態様として、前記外輪の外周面と前記ハウジングの間には、弾性部材が介在している。弾性部材によって外輪の径方向の振動が吸収され、いわゆるラトル音の発生が抑制される。 As a desirable aspect of the power transmission device according to one aspect, an elastic member is interposed between the outer peripheral surface of the outer ring and the housing. The elastic member absorbs the radial vibration of the outer ring and suppresses the generation of so-called rattle noise.

一態様に係る動力伝達装置の望ましい態様として、前記従動プーリにおいて前記外輪の端面と対向する側面には、凹部が形成され、前記外輪には、前記凹部内に向かって延出する延出部が形成され、前記延出部の端部は、前記凹部内に入り込み、前記延出部の端部と前記凹部との間は、微小隙間によるラビリンス構造となっている。これにより、従動プーリとベルトとの摩耗粉が第１軸受及び第２軸受内に侵入し難くなる。 As a desirable aspect of the power transmission device according to one aspect, a recess is formed on the side surface of the driven pulley facing the end surface of the outer ring, and the outer ring has an extending portion extending toward the inside of the recess. The end of the extending portion is formed, and the end portion of the extending portion enters the recess, and the space between the end portion of the extending portion and the recess has a labyrinth structure with a minute gap. This makes it difficult for wear debris from the driven pulley and the belt to enter the first bearing and the second bearing.

一態様に係る動力伝達装置の望ましい態様として、前記外輪に固定されるとともに、前記従動プーリの側面に向かって延出し、前記外輪と前記従動プーリとの隙間を閉塞するシールド部材を備え、前記従動プーリにおいて前記外輪の端面と対向する側面には、凹部が形成され、前記シールド部材の端部は、前記凹部内に入り込み、前記シールド部材の端部と前記凹部との間は、微小隙間によるラビリンス構造となっている。これにより、従動プーリとベルトとの摩耗粉が第１軸受及び第２軸受内に侵入し難くなる。 As a desirable aspect of the power transmission device according to one aspect, the driven member is provided with a shield member which is fixed to the outer ring and extends toward the side surface of the driven pulley to close the gap between the outer ring and the driven pulley. A recess is formed on the side surface of the pulley facing the end surface of the outer ring, the end of the shield member enters the recess, and the labyrinth between the end of the shield member and the recess is provided by a minute gap. It has a structure. This makes it difficult for wear debris from the driven pulley and the belt to enter the first bearing and the second bearing.

一態様に係る動力伝達装置の望ましい態様として、前記凹部内には、グリスが充填されている。これにより摩耗粉がグリスに吸着されるため、摩耗粉が第１軸受及び第２軸受内にさらに侵入し難くなる。 As a desirable aspect of the power transmission device according to one aspect, the recess is filled with grease. As a result, the wear debris is adsorbed on the grease, so that the wear debris is less likely to enter the first bearing and the second bearing.

一態様に係る動力伝達装置の望ましい態様として、前記外輪における前記予圧付与部材側を向く端部には、前記ナットの外周面に摺接する第１シール部材が設けられている。これにより、予圧付与部材側にある異物が第１軸受及び第２軸受内に侵入し難くなる。 As a desirable aspect of the power transmission device according to one aspect, a first seal member that is in sliding contact with the outer peripheral surface of the nut is provided at an end portion of the outer ring facing the preload applying member side. As a result, foreign matter on the preload applying member side is less likely to enter the first bearing and the second bearing.

一態様に係る動力伝達装置の望ましい態様として、前記第１シール部材は、前記外輪の端部に固定される芯金と、前記芯金に支持される内周シール用弾性体と、を有し、前記芯金は、前記外輪の外周面に嵌合する筒状の外周嵌合部を有し、前記外輪の外周面には、径方向内側に窪み、前記外周嵌合部を収容する凹部が形成されている。これにより、外周嵌合部が凹部内に収容され、外周嵌合部がハウジングに当接して外輪の摺動を阻害する、ということを防止することができる。 As a desirable aspect of the power transmission device according to one aspect, the first seal member has a core metal fixed to the end of the outer ring and an elastic body for inner circumference sealing supported by the core metal. The core metal has a tubular outer peripheral fitting portion that fits on the outer peripheral surface of the outer ring, and the outer peripheral surface of the outer ring is recessed inward in the radial direction and has a recess that accommodates the outer peripheral fitting portion. It is formed. As a result, it is possible to prevent the outer peripheral fitting portion from being housed in the recess and the outer peripheral fitting portion coming into contact with the housing to hinder the sliding of the outer ring.

一態様に係る動力伝達装置の望ましい態様として、前記外輪の外周面と前記ハウジングの内周面との間を閉塞する外周シール用弾性体を備え、前記外周シール用弾性体は、前記外周嵌合部の外周面に固定されて前記ハウジングの内周面に摺接する。外周シール用弾性体によれば、ハウジングと外輪との間からグリスが漏出することが抑制され、外輪の摺動性を確保できる。また、外周シール用弾性体によって外輪の径方向の振動が吸収され、いわゆるラトル音の発生が抑制される。さらに、芯金を外輪に組み付けると、外周シール用弾性体も併せて組み付けられるため、組み付け作業の工数が削減する。 As a desirable aspect of the power transmission device according to one aspect, an outer peripheral sealing elastic body that closes between the outer peripheral surface of the outer ring and the inner peripheral surface of the housing is provided, and the outer peripheral sealing elastic body is fitted to the outer circumference. It is fixed to the outer peripheral surface of the portion and slides into the inner peripheral surface of the housing. According to the elastic body for the outer peripheral seal, the leakage of grease from between the housing and the outer ring is suppressed, and the slidability of the outer ring can be ensured. Further, the elastic body for the outer peripheral seal absorbs the vibration in the radial direction of the outer ring, and the generation of so-called rattle noise is suppressed. Further, when the core metal is attached to the outer ring, the elastic body for the outer peripheral seal is also attached, so that the man-hours for the assembling work are reduced.

一態様に係る動力伝達装置の望ましい態様として、前記予圧付与部材と前記外輪との間に介在して、前記中心軸方向の高負荷を吸収する高負荷吸収部を備え、前記予圧付与部材は、前記中心軸方向で切った断面積が前記高負荷吸収部よりも小さく、前記予圧付与部材と前記高負荷吸収部は、前記芯金に支持されている。これにより、高負荷吸収部と予圧付与部材を組み付けた場合、予圧付与部材が変形して外輪を押圧し、軸受に予圧を与える。一方で、ボールねじ装置に高負荷が作用した場合、高負荷吸収部が吸収する。これにより、予圧付与部材に高負荷が作用して破断する、ということが回避される。また、芯金を外輪に組み付けると、予圧付与部材と高負荷吸収部も組み付けられるため、組み付け作業の工数が低減する。 As a desirable aspect of the power transmission device according to one aspect, the preload applying member is provided with a high load absorbing portion that is interposed between the preload applying member and the outer ring to absorb a high load in the central axis direction. The cross-sectional area cut in the central axis direction is smaller than that of the high load absorbing portion, and the preload applying member and the high load absorbing portion are supported by the core metal. As a result, when the high load absorbing portion and the preload applying member are assembled, the preload applying member is deformed to press the outer ring and preload the bearing. On the other hand, when a high load acts on the ball screw device, the high load absorbing portion absorbs the load. As a result, it is avoided that a high load acts on the preload applying member and the member breaks. Further, when the core metal is assembled to the outer ring, the preload applying member and the high load absorbing portion are also assembled, so that the man-hours for the assembling work are reduced.

一態様に係る動力伝達装置の望ましい態様として、前記第１軸受又は前記第２軸受の外輪における前記従動プーリ側を向く端部には、前記ナットの外周面に摺接する第２シール部材が設けられている。これにより、従動プーリとベルトとの摩耗粉が第１軸受及び第２軸受内に侵入し難くなる。 As a desirable aspect of the power transmission device according to one aspect, a second seal member that is in sliding contact with the outer peripheral surface of the nut is provided at an end portion of the outer ring of the first bearing or the second bearing that faces the driven pulley side. ing. This makes it difficult for wear debris from the driven pulley and the belt to enter the first bearing and the second bearing.

本開示の動力伝達装置は、軸受のモーメント荷重に対する剛性を低減しているため、ボールねじ装置に入力されるモーメント荷重が低減する。 Since the power transmission device of the present disclosure reduces the rigidity of the bearing with respect to the moment load, the moment load input to the ball screw device is reduced.

図１は、実施形態１の動力伝達装置を有する電動パワーステアリング装置の模式図である。FIG. 1 is a schematic view of an electric power steering device having the power transmission device of the first embodiment. 図２は、実施形態１のラックの正面図である。FIG. 2 is a front view of the rack of the first embodiment. 図３は、実施形態１の動力伝達装置を、ねじ軸と電動モータの出力軸を含む平面で切った場合の断面図である。FIG. 3 is a cross-sectional view of the power transmission device of the first embodiment cut by a plane including a screw shaft and an output shaft of an electric motor. 図４は、実施形態１の動力伝達装置を、ねじ軸を含む平面であって図３の断面図と直交する角度の平面で切った場合の断面図である。FIG. 4 is a cross-sectional view of the power transmission device of the first embodiment when the power transmission device is cut along a plane including a screw shaft and at an angle orthogonal to the cross-sectional view of FIG. 図５は、第１軸受及び第２軸受の接触角の延長線を説明するための断面図である。FIG. 5 is a cross-sectional view for explaining an extension line of the contact angles of the first bearing and the second bearing. 図６は、変形例１の動力伝達装置の断面図である。FIG. 6 is a cross-sectional view of the power transmission device of the first modification. 図７は、変形例２の動力伝達装置の断面図である。FIG. 7 is a cross-sectional view of the power transmission device of the second modification. 図８は、実施形態２の動力伝達装置の断面図である。FIG. 8 is a cross-sectional view of the power transmission device of the second embodiment. 図９は、変形例３の動力伝達装置の断面図であるFIG. 9 is a cross-sectional view of the power transmission device of the modified example 3. 図１０は、変形例３のナットの一部を拡大しかつ斜視した斜視図である。FIG. 10 is an enlarged and perspective view of a part of the nut of the modified example 3. 図１１は、実施形態３の動力伝達装置の断面図である。FIG. 11 is a cross-sectional view of the power transmission device of the third embodiment. 図１２は、実施形態４の動力伝達装置の断面図である。FIG. 12 is a cross-sectional view of the power transmission device of the fourth embodiment. 図１３は、実施形態５の動力伝達装置の断面図である。FIG. 13 is a cross-sectional view of the power transmission device of the fifth embodiment. 図１４は、実施形態６の動力伝達装置の断面図である。FIG. 14 is a cross-sectional view of the power transmission device of the sixth embodiment. 図１５は、実施形態７の動力伝達装置の断面図である。FIG. 15 is a cross-sectional view of the power transmission device of the seventh embodiment. 図１６は、実施形態８の動力伝達装置の断面図である。FIG. 16 is a cross-sectional view of the power transmission device of the eighth embodiment. 図１７は、実施形態９の動力伝達装置の断面図である。FIG. 17 is a cross-sectional view of the power transmission device of the ninth embodiment. 図１８は、図１７の予圧付与部材と高負荷吸収部とのみを抽出し、中心軸方向から視た模式図である。FIG. 18 is a schematic view in which only the preload applying member and the high load absorbing portion of FIG. 17 are extracted and viewed from the central axis direction.

以下、本発明につき図面を参照しつつ詳細に説明する。なお、下記の発明を実施するための形態（以下、実施形態という）により本発明が限定されるものではない。また、下記実施形態における構成要素には、当業者が容易に想定できるもの、実質的に同一のもの、いわゆる均等の範囲のものが含まれる。さらに、下記実施形態で開示した構成要素は適宜組み合わせることが可能である。 Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments for carrying out the following inventions (hereinafter referred to as embodiments). In addition, the components in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, that is, those in a so-called equal range. Further, the components disclosed in the following embodiments can be appropriately combined.

（実施形態１）
図１は、実施形態１のボールねじ装置を有する電動パワーステアリング装置の模式図である。図１に示すように、電動パワーステアリング装置８０は、ステアリングホイール８１と、ステアリングシャフト８２と、ユニバーサルジョイント８４と、ロアシャフト８５と、ユニバーサルジョイント８６と、ピニオンシャフト８７と、ピニオン８８ａと、ラック８８ｂと、を備える。 (Embodiment 1)
FIG. 1 is a schematic view of an electric power steering device having the ball screw device of the first embodiment. As shown in FIG. 1, the electric power steering device 80 includes a steering wheel 81, a steering shaft 82, a universal joint 84, a lower shaft 85, a universal joint 86, a pinion shaft 87, a pinion 88a, and a rack 88b. And.

ステアリングホイール８１は、ステアリングシャフト８２に連結される。ステアリングシャフト８２の一端は、ステアリングホイール８１に連結される。ステアリングシャフト８２の他端は、ユニバーサルジョイント８４に連結される。ロアシャフト８５の一端は、ユニバーサルジョイント８４を介してステアリングシャフト８２に連結される。ロアシャフト８５の他端は、ユニバーサルジョイント８６を介してピニオンシャフト８７に連結される。ピニオンシャフト８７は、ピニオン８８ａに連結される。ピニオン８８ａは、ラック８８ｂに噛み合う。ピニオン８８ａが回転すると、ラック８８ｂが車両の車幅方向に移動する。ピニオン８８ａ及びラック８８ｂは、ピニオンシャフト８７に伝達された回転運動を直進運動に変換する。ラック８８ｂの両端には、タイロッド８９が連結される。ラック８８ｂが移動することで車輪の角度が変化する。なお、ステアリングホイール８１の操作が電気信号に変換され、電気信号によって車輪の角度が変化させられてもよい。すなわち、電動パワーステアリング装置８０に、ステアバイワイヤシステムを適用してもよい。 The steering wheel 81 is connected to the steering shaft 82. One end of the steering shaft 82 is connected to the steering wheel 81. The other end of the steering shaft 82 is connected to the universal joint 84. One end of the lower shaft 85 is connected to the steering shaft 82 via a universal joint 84. The other end of the lower shaft 85 is connected to the pinion shaft 87 via a universal joint 86. The pinion shaft 87 is connected to the pinion 88a. The pinion 88a meshes with the rack 88b. When the pinion 88a rotates, the rack 88b moves in the vehicle width direction. The pinion 88a and the rack 88b convert the rotational motion transmitted to the pinion shaft 87 into a straight motion. Tie rods 89 are connected to both ends of the rack 88b. The angle of the wheel changes as the rack 88b moves. The operation of the steering wheel 81 may be converted into an electric signal, and the angle of the wheel may be changed by the electric signal. That is, the steer-by-wire system may be applied to the electric power steering device 80.

また、電動パワーステアリング装置８０は、電動モータ９３と、トルクセンサ９４と、ＥＣＵ（Electronic Control Unit）９０と、を備える。電動モータ９３は、例えばブラシレスモータであるが、ブラシ（摺動子）及びコミュテータ（整流子）を備えるモータであってもよい。電動モータ９３は、後述するハウジング１００内に配置される。トルクセンサ９４は、例えばピニオン８８ａに取り付けられている。トルクセンサ９４は、ピニオン８８ａに伝達された操舵トルクをＣＡＮ（Controller Area Network）通信によりＥＣＵ９０に出力する。車速センサ９５は、電動パワーステアリング装置８０が搭載される車両の走行速度（車速）を検出する。車速センサ９５は、車体に備えられ、ＣＡＮ通信により走行速度（車速）をＥＣＵ９０に出力する。電動モータ９３、トルクセンサ９４及び車速センサ９５は、ＥＣＵ９０と電気的に接続される。 Further, the electric power steering device 80 includes an electric motor 93, a torque sensor 94, and an ECU (Electronic Control Unit) 90. The electric motor 93 is, for example, a brushless motor, but may be a motor including a brush (slider) and a commutator (commutator). The electric motor 93 is arranged in the housing 100 described later. The torque sensor 94 is attached to, for example, a pinion 88a. The torque sensor 94 outputs the steering torque transmitted to the pinion 88a to the ECU 90 by CAN (Controller Area Network) communication. The vehicle speed sensor 95 detects the traveling speed (vehicle speed) of the vehicle on which the electric power steering device 80 is mounted. The vehicle speed sensor 95 is provided on the vehicle body and outputs the traveling speed (vehicle speed) to the ECU 90 by CAN communication. The electric motor 93, the torque sensor 94, and the vehicle speed sensor 95 are electrically connected to the ECU 90.

ＥＣＵ９０は、電動モータ９３の動作を制御する。ＥＣＵ９０は、トルクセンサ９４及び車速センサ９５のそれぞれから信号を取得する。ＥＣＵ９０には、イグニッションスイッチ９８がオンの状態で、電源装置９９（例えば車載のバッテリ）から電力が供給される。ＥＣＵ９０は、操舵トルク及び車速に基づいて補助操舵指令値を算出する。ＥＣＵ９０は、補助操舵指令値に基づいて電動モータ９３へ供給する電力値を調節する。ＥＣＵ９０は、電動モータ９３から誘起電圧の情報又は電動モータ９３に設けられたレゾルバ等から出力される情報を取得する。 The ECU 90 controls the operation of the electric motor 93. The ECU 90 acquires signals from each of the torque sensor 94 and the vehicle speed sensor 95. Electric power is supplied to the ECU 90 from the power supply device 99 (for example, an in-vehicle battery) with the ignition switch 98 turned on. The ECU 90 calculates the auxiliary steering command value based on the steering torque and the vehicle speed. The ECU 90 adjusts the electric power value supplied to the electric motor 93 based on the auxiliary steering command value. The ECU 90 acquires information on the induced voltage from the electric motor 93 or information output from a resolver or the like provided in the electric motor 93.

図２は、実施形態１のラックの正面図である。図３は、実施形態１の動力伝達装置を、ねじ軸と電動モータの出力軸を含む平面で切った場合の断面図である。図４は、実施形態１の動力伝達装置を、ねじ軸を含む平面であって図３の断面図と直交する角度の平面で切った場合の断面図である。図５は、第１軸受及び第２軸受の接触角の延長線を説明するための断面図である。図２に示すように、ハウジング１００は、車幅方向に延在する筒状の部品である。ハウジング１００は、例えばアルミニウム合金又はマグネシウム合金等の軽金属で形成される。ハウジング１００は、第１本体１０１と、第２本体１０３と、第３本体１０５と、を備える。第１本体１０１と第２本体１０３と第３本体１０５とは、ボルトにより締結されて一体となっている。 FIG. 2 is a front view of the rack of the first embodiment. FIG. 3 is a cross-sectional view of the power transmission device of the first embodiment cut by a plane including a screw shaft and an output shaft of an electric motor. FIG. 4 is a cross-sectional view of the power transmission device of the first embodiment when the power transmission device is cut along a plane including a screw shaft and at an angle orthogonal to the cross-sectional view of FIG. FIG. 5 is a cross-sectional view for explaining an extension line of the contact angles of the first bearing and the second bearing. As shown in FIG. 2, the housing 100 is a tubular component extending in the vehicle width direction. The housing 100 is made of a light metal such as an aluminum alloy or a magnesium alloy. The housing 100 includes a first main body 101, a second main body 103, and a third main body 105. The first main body 101, the second main body 103, and the third main body 105 are fastened with bolts to be integrated.

図３に示すように、第１本体１０１及び第２本体１０３に跨って、動力伝達装置１が収容されている。第３本体１０５には、電動モータ９３が収容されている。 As shown in FIG. 3, the power transmission device 1 is housed across the first main body 101 and the second main body 103. An electric motor 93 is housed in the third main body 105.

動力伝達装置１は、ハウジング１００の第１本体１０１及び第２本体１０３と、ボールねじ装置１０と、プーリ装置２０と、第１軸受３０ａと、第２軸受３０ｂと、予圧付与部材４０ａ、４０ｂと、を備える。 The power transmission device 1 includes a first main body 101 and a second main body 103 of the housing 100, a ball screw device 10, a pulley device 20, a first bearing 30a, a second bearing 30b, and preload applying members 40a and 40b. , Equipped with.

ボールねじ装置１０は、ねじ軸１１と、ナット１３と、複数のボール１５と、を備える。ねじ軸１１の外周面には、第２ねじ溝１２が形成されている。ねじ軸１１は、車幅方向に延在し、ナット１３を貫通している。ねじ軸１１は、ラック８８ｂの一部であり、中心軸ＡＸを中心に回転しない。すなわち、ねじ軸１１は、ラック８８ｂと一体である。 The ball screw device 10 includes a screw shaft 11, a nut 13, and a plurality of balls 15. A second thread groove 12 is formed on the outer peripheral surface of the screw shaft 11. The screw shaft 11 extends in the vehicle width direction and penetrates the nut 13. The screw shaft 11 is a part of the rack 88b and does not rotate about the central shaft AX. That is, the screw shaft 11 is integrated with the rack 88b.

ナット１３の内周面には、第１ねじ溝１４が形成されている。ナット１３は、第１軸受３０ａ及び第２軸受３０ｂに支持され、中心軸ＡＸを中心に回転自在となっている。ボール１５は、ナット１３の第１ねじ溝１４とねじ軸１１の第２ねじ溝１２との間に複数個配置される。ボール１５は、ナット１３の第１ねじ溝１４と、ねじ軸１１の第２ねじ溝１２とで形成される転動路を無限循環する。そして、ナット１３が回転すると、ねじ軸１１（ラック８８ｂ）が車幅方向に移動する。これにより、回転運動がラック８８ｂの直動に変換される。 A first thread groove 14 is formed on the inner peripheral surface of the nut 13. The nut 13 is supported by the first bearing 30a and the second bearing 30b, and is rotatable about the central axis AX. A plurality of balls 15 are arranged between the first thread groove 14 of the nut 13 and the second thread groove 12 of the screw shaft 11. The ball 15 infinitely circulates in a rolling path formed by the first thread groove 14 of the nut 13 and the second thread groove 12 of the screw shaft 11. Then, when the nut 13 rotates, the screw shaft 11 (rack 88b) moves in the vehicle width direction. As a result, the rotational motion is converted into the linear motion of the rack 88b.

以下の説明において、ナット１３の中心軸ＡＸと平行な方向を中心軸ＡＸ方向という。中心軸ＡＸに対して直交する方向は、単に径方向という。径方向は、放射方向とも呼ばれる方向である。 In the following description, the direction parallel to the central axis AX of the nut 13 is referred to as the central axis AX direction. The direction orthogonal to the central axis AX is simply called the radial direction. The radial direction is also called the radial direction.

プーリ装置２０は、電動モータ９３の動力をナット１３に伝達する。プーリ装置２０は、駆動プーリ２１と、従動プーリ２３と、ベルト２５と、を備える。駆動プーリ２１は、円筒状の部品であり、電動モータ９３の出力軸９３ａに固定されている。従動プーリ２３は、中心軸ＡＸを中心とする円筒状に形成されている。従動プーリ２３の内周側は、ナット１３と連続している。また、従動プーリ２３は、ナット１３と同一の金属材料で一体加工されている。よって、従動プーリ２３は、ナット１３と一体化している。ベルト２５は、無端ベルトである。ベルト２５は、駆動プーリ２１及び従動プーリ２３に巻き掛けられている。具体的に、ベルト２５は、駆動プーリ２１の外周面２１ａ及び従動プーリ２３の外周面２３ａに掛けられている。ベルト２５は、外周面２１ａと従動プーリ２３とが互いに近づくような荷重、つまり張力を発揮している。 The pulley device 20 transmits the power of the electric motor 93 to the nut 13. The pulley device 20 includes a drive pulley 21, a driven pulley 23, and a belt 25. The drive pulley 21 is a cylindrical component and is fixed to the output shaft 93a of the electric motor 93. The driven pulley 23 is formed in a cylindrical shape centered on the central axis AX. The inner peripheral side of the driven pulley 23 is continuous with the nut 13. Further, the driven pulley 23 is integrally processed with the same metal material as the nut 13. Therefore, the driven pulley 23 is integrated with the nut 13. The belt 25 is an endless belt. The belt 25 is wound around the drive pulley 21 and the driven pulley 23. Specifically, the belt 25 is hung on the outer peripheral surface 21a of the drive pulley 21 and the outer peripheral surface 23a of the driven pulley 23. The belt 25 exerts a load, that is, a tension so that the outer peripheral surface 21a and the driven pulley 23 come close to each other.

図４に示すように、従動プーリ２３の外周面２３ａにおける中心軸ＡＸ方向の長さＬ１は、ベルト２５における中心軸ＡＸ方向の長さＬ２と一致している。また、従動プーリ２３の第１端面２３ｂと第２端面２３ｃとには、外周面２３ａよりも径方向外側に突出するガイド２４ａ、２４ｂが設けられている。これにより、ベルト２５が中心軸ＡＸ方向に位置ずれしないように規制されている。 As shown in FIG. 4, the length L1 of the driven pulley 23 in the central axis AX direction on the outer peripheral surface 23a coincides with the length L2 of the belt 25 in the central axis AX direction. Further, the first end surface 23b and the second end surface 23c of the driven pulley 23 are provided with guides 24a and 24b protruding radially outward from the outer peripheral surface 23a. As a result, the belt 25 is regulated so as not to be displaced in the central axis AX direction.

上記構成によれば、電動モータ９３が回転駆動すると、電動モータ９３で生じた動力がプーリ装置２０を介してナット１３に伝達される。そして、第１軸受３０ａ及び第２軸受３０ｂに支持されるナット１３が回転する。ナット１３が回転すると、ラック８８ｂ（ねじ軸１１）に軸方向の力が作用する。これにより、ラック８８ｂを移動させるために要するピニオン８８ａ（ステアリングホイール８１）の力が小さくなる。すなわち、電動パワーステアリング装置８０は、ラックアシスト式である。 According to the above configuration, when the electric motor 93 is rotationally driven, the power generated by the electric motor 93 is transmitted to the nut 13 via the pulley device 20. Then, the nut 13 supported by the first bearing 30a and the second bearing 30b rotates. When the nut 13 rotates, an axial force acts on the rack 88b (screw shaft 11). As a result, the force of the pinion 88a (steering wheel 81) required to move the rack 88b is reduced. That is, the electric power steering device 80 is a rack assist type.

第１軸受３０ａ及び第２軸受３０ｂは、それぞれアンギュラ玉軸受である。第１軸受３０ａは、第２本体１０３に収容され、第２本体１０３とナット１３との間に配置されている。第２軸受３０ｂは、第１本体１０１に収容され、第１本体１０１とナット１３の間に配置されている。第１軸受３０ａ及び第２軸受３０ｂは、正面組合せとなるように配置されている。また、第１軸受３０ａと第２軸受３０ｂとの間には、従動プーリ２３が配置されている。つまり、第１軸受３０ａと第２軸受３０ｂは、中心軸ＡＸ方向の両側から従動プーリ２３を挟んでいる。以下、中心軸ＡＸ方向において従動プーリ２３から視て第１軸受３０ａが配置される方向を中心軸ＡＸ方向の第１方向側（図４の左側）と称し、第２軸受３０ｂが配置されている方向を中心軸ＡＸ方向の第２方向側（図４の右側）と称する。 The first bearing 30a and the second bearing 30b are angular contact ball bearings, respectively. The first bearing 30a is housed in the second main body 103 and is arranged between the second main body 103 and the nut 13. The second bearing 30b is housed in the first main body 101 and is arranged between the first main body 101 and the nut 13. The first bearing 30a and the second bearing 30b are arranged so as to form a frontal combination. Further, a driven pulley 23 is arranged between the first bearing 30a and the second bearing 30b. That is, the first bearing 30a and the second bearing 30b sandwich the driven pulley 23 from both sides in the central axis AX direction. Hereinafter, the direction in which the first bearing 30a is arranged when viewed from the driven pulley 23 in the central axis AX direction is referred to as the first direction side (left side in FIG. 4) in the central axis AX direction, and the second bearing 30b is arranged. The direction is referred to as the second direction side (right side in FIG. 4) in the central axis AX direction.

図４に示すように、第１軸受３０ａ及び第２軸受３０ｂのそれぞれは、外輪３１ａ、３１ｂと、内輪３３ａ、３３ｂと、複数の転動体３５ａ、３５ｂと、を備える。 As shown in FIG. 4, each of the first bearing 30a and the second bearing 30b includes outer rings 31a and 31b, inner rings 33a and 33b, and a plurality of rolling elements 35a and 35b, respectively.

外輪３１ａ、３１ｂは、ハウジング１００の内周面に嵌め合わされている。詳細には、外輪３１ａは、第２本体１０３の内周面１０３ｂに隙間嵌めされている。外輪３１ｂは、第１本体１０１の内周面１０１ｂに隙間嵌めされている。よって、外輪３１ａ、３１ｂは、内周面１０１ｂ、１０３ｂに対して中心軸ＡＸ方向に摺動自在となっている。さらに、外輪３１ａ、３１ｂは、予圧付与部材４０ａ、４０ｂにより互いに近づくように押圧されている。具体的には、外輪３１ａは、予圧付与部材４０ａによって第２方向側に押圧されている。また、外輪３１ｂは、予圧付与部材４０ｂによって第１方向側に押圧されている。これにより、第１軸受３０ａにおいて、転動体３５ａが外輪軌道面３１ｃと内輪軌道面３３ｃとに接触し、第１軸受３０ａに予圧が付与されている。同様に、第２軸受３０ｂにおいて、転動体３５ｂが外輪軌道面３１ｄと内輪軌道面３３ｄとに接触し、第２軸受３０ｂに予圧が付与されている。そして、転動体３５ａ、３５ｂには、予圧付与部材４０ａ、４０ｂの押圧による荷重が作用し、内部隙間が負の状態となっている。なお、本実施形態においては、外輪３１ａ、３１ｂは、ハウジング１００に隙間嵌めされているが、外輪３１ａ、３１ｂがハウジング１００に対して摺動できればよく、ハウジング１００の内周面１０１ｂ、１０３ｂの内径と外輪３１ａ、３１ｂの外径が同一であってもよい。 The outer rings 31a and 31b are fitted to the inner peripheral surface of the housing 100. Specifically, the outer ring 31a is gap-fitted to the inner peripheral surface 103b of the second main body 103. The outer ring 31b is gap-fitted to the inner peripheral surface 101b of the first main body 101. Therefore, the outer rings 31a and 31b are slidable with respect to the inner peripheral surfaces 101b and 103b in the central axis AX direction. Further, the outer rings 31a and 31b are pressed by the preload applying members 40a and 40b so as to approach each other. Specifically, the outer ring 31a is pressed toward the second direction by the preload applying member 40a. Further, the outer ring 31b is pressed toward the first direction by the preload applying member 40b. As a result, in the first bearing 30a, the rolling element 35a comes into contact with the outer ring raceway surface 31c and the inner ring raceway surface 33c, and a preload is applied to the first bearing 30a. Similarly, in the second bearing 30b, the rolling element 35b comes into contact with the outer ring raceway surface 31d and the inner ring raceway surface 33d, and a preload is applied to the second bearing 30b. Then, a load due to the pressing of the preload applying members 40a and 40b acts on the rolling elements 35a and 35b, and the internal gap is in a negative state. In the present embodiment, the outer rings 31a and 31b are gap-fitted in the housing 100, but it is sufficient that the outer rings 31a and 31b can slide with respect to the housing 100, and the inner diameters of the inner peripheral surfaces 101b and 103b of the housing 100 need to be slid. And the outer diameters of the outer rings 31a and 31b may be the same.

予圧が与えられている状態で、外輪３１ａの第２端面３１ｅは、従動プーリ２３の第１側面２３ｄと離隔している。また、外輪３１ｂの第１端面３１ｆは、従動プーリ２３の第２側面２３ｅと離隔している。つまり、外輪３１ａと従動プーリ２３との間には隙間Ｓ１が形成され、外輪３１ｂと従動プーリ２３との間には隙間Ｓ２が形成されている。 The second end surface 31e of the outer ring 31a is separated from the first side surface 23d of the driven pulley 23 in a state where the preload is applied. Further, the first end surface 31f of the outer ring 31b is separated from the second side surface 23e of the driven pulley 23. That is, a gap S1 is formed between the outer ring 31a and the driven pulley 23, and a gap S2 is formed between the outer ring 31b and the driven pulley 23.

これにより、外輪３１ａ、３１ｂの外形に関し、所定の大きさよりも中心軸ＡＸ方向であって従動プーリ２３側に大きく形成される、といった寸法誤差があったとしても隙間Ｓ１、Ｓ２に吸収され、従動プーリ２３に接触しない。一方で、外輪３１ａ、３１ｂの外形に関し、所定の大きさよりも中心軸ＡＸ方向であって従動プーリ２３側に小さく形成される、といった寸法誤差があった場合、隙間Ｓ１、Ｓ２が大きくなるだけで、外輪３１ａ、３１ｂの位置は変位しない。よって、外輪３１ａ、３１ｂが従動プーリ２３に接触して外輪軌道面３１ｃ、３１ｄが変位し転動体３５ａ、３５ｂに作用する荷重が変動する、ということが回避される。 As a result, even if there is a dimensional error such that the outer shapes of the outer rings 31a and 31b are formed larger on the driven pulley 23 side in the central axis AX direction than the predetermined size, they are absorbed by the gaps S1 and S2 and driven. Does not contact the pulley 23. On the other hand, if there is a dimensional error such that the outer shapes of the outer rings 31a and 31b are formed smaller on the driven pulley 23 side in the central axis AX direction than the predetermined size, the gaps S1 and S2 are only increased. , The positions of the outer rings 31a and 31b are not displaced. Therefore, it is avoided that the outer rings 31a and 31b come into contact with the driven pulley 23 and the outer ring raceway surfaces 31c and 31d are displaced and the load acting on the rolling elements 35a and 35b fluctuates.

また、外輪３１ａ、３１ｂの外形に関し、所定の大きさよりも中心軸ＡＸ方向であって従動プーリ２３と反対側に大きく又は小さく形成されている場合には、予圧付与部材４０ａ、４０ｂに吸収され、外輪軌道面３１ｃ、３１ｄが変位しない。以上から、外輪３１ａ、３１ｂの外形に寸法誤差があったとしても、転動体３５ａ、３５ｂに作用する予圧付与部材４０ａ、４０ｂの荷重が変動せず、予圧量が所定量となる。つまり、第１軸受３０ａと、第２軸受３０ｂに付与される予圧量は、予圧付与部材４０ａ、４０ｂの押圧のみとなり、定圧予圧となる。 Further, regarding the outer shapes of the outer rings 31a and 31b, if they are formed larger or smaller in the direction of the central axis AX than the predetermined size and on the side opposite to the driven pulley 23, they are absorbed by the preload applying members 40a and 40b. The outer ring raceway surfaces 31c and 31d are not displaced. From the above, even if there is a dimensional error in the outer shapes of the outer rings 31a and 31b, the load of the preload applying members 40a and 40b acting on the rolling elements 35a and 35b does not fluctuate, and the preload amount becomes a predetermined amount. That is, the preload applied to the first bearing 30a and the second bearing 30b is only the pressing of the preload applying members 40a and 40b, which is a constant pressure preload.

外輪３１ａの外周面と第２本体１０３の内周面１０３ｂとの間には、グリスが塗布されている。また、外輪３１ｂの外周面と第１本体１０１の内周面１０１ｂとの間には、グリスが塗布されている。外輪３１ａ、３１ｂの外周面には、径方向内側に窪み、かつ、周方向に延在するグリス用溝３６ａ、３６ｂが形成されている。グリス用溝３６ａ、３６ｂの内部には、グリスが保持されている。よって、より多くのグリスが外輪３１ａの外周面と第２本体１０３の内周面１０３ｂとの間に介在している。同様に、より多くのグリスが外輪３１ｂの外周面と第１本体１０１の内周面１０１ｂとの間に介在している。よって、外輪３１ａ、３１ｂは内周面１０１ｂに対して摺動し易く、摩擦熱が発生し難い。そして、外輪３１ａ、３１ｂが熱膨張して予圧量が変動する、ということが抑制される。尚、外輪３１ａ、３１ｂが内周面１０３ｂ、１０１ｂに対して中心軸ＡＸを中心に回転（所謂クリープ）することを防止するために、外輪３１ａ、３１ｂの外周面又は端面にキー溝を設けたり、外輪３１ａ、３１ｂをピン止めしたりすることも可能である。 Grease is applied between the outer peripheral surface of the outer ring 31a and the inner peripheral surface 103b of the second main body 103. Further, grease is applied between the outer peripheral surface of the outer ring 31b and the inner peripheral surface 101b of the first main body 101. On the outer peripheral surfaces of the outer rings 31a and 31b, grease grooves 36a and 36b that are recessed inward in the radial direction and extend in the circumferential direction are formed. Grease is held inside the grooves 36a and 36b for grease. Therefore, more grease is interposed between the outer peripheral surface of the outer ring 31a and the inner peripheral surface 103b of the second main body 103. Similarly, more grease is interposed between the outer peripheral surface of the outer ring 31b and the inner peripheral surface 101b of the first main body 101. Therefore, the outer rings 31a and 31b are likely to slide with respect to the inner peripheral surface 101b, and frictional heat is less likely to be generated. Then, it is suppressed that the outer rings 31a and 31b are thermally expanded and the preload amount fluctuates. In order to prevent the outer rings 31a and 31b from rotating (so-called creep) around the central axis AX with respect to the inner peripheral surfaces 103b and 101b, a key groove may be provided on the outer peripheral surface or the end surface of the outer rings 31a and 31b. , The outer rings 31a and 31b can also be pinned.

図５に示すように、外輪３１ａ、３１ｂの内周面には、外輪軌道面３１ｃ、３１ｄが形成されている。また、外輪３１ａ、３１ｂの内周面であって外輪軌道面３１ｃ、３１ｄの内側には、転動体３５ａ、３５ｂを保持する保持器の爪部が引っ掛かる溝が形成されている。 As shown in FIG. 5, outer ring raceway surfaces 31c and 31d are formed on the inner peripheral surfaces of the outer rings 31a and 31b. Further, on the inner peripheral surfaces of the outer rings 31a and 31b, inside the outer ring raceway surfaces 31c and 31d, a groove is formed in which the claws of the cage holding the rolling elements 35a and 35b are caught.

内輪３３ａ、３３ｂは、ナット１３と同じ材料で形成され、ナット１３と一体化している。つまり、ナット１３の外周面１３ａには、複列の内輪軌道面３３ｃ、３３ｄが形成されている。内輪軌道面３３ｃ、３３ｄは、ズブ焼き、浸炭処理、高周波処理などの硬化処理が施されており、耐久性が向上している。なお、本実施形態では、内輪３３ａ、３３ｂがナット１３と一体化しているが、ナット１３と別体である内輪を用いてもよい。 The inner rings 33a and 33b are made of the same material as the nut 13 and are integrated with the nut 13. That is, a double row of inner ring raceway surfaces 33c and 33d are formed on the outer peripheral surface 13a of the nut 13. The inner ring raceway surfaces 33c and 33d are subjected to hardening treatments such as shaving, carburizing, and high frequency treatment to improve durability. In the present embodiment, the inner rings 33a and 33b are integrated with the nut 13, but an inner ring that is separate from the nut 13 may be used.

転動体３５ａ、３５ｂは、ボールである。転動体３５ａは、外輪３１ａと内輪３３ａとの間に配置され、外輪３１ａの外輪軌道面３１ｃと内輪３３ａの内輪軌道面３３ｃとに接触している。なお、中心軸ＡＸに直交し、かつ、転動体３５ａの中心Ｃ１を通る仮想線を基準線ＣＮａという。転動体３５ａと外輪軌道面３１ｃとの接点Ｐ１と、転動体３５ａと内輪軌道面３３ｃとの接点Ｐ２と、を結ぶ仮想線の延長線を、第１軸受３０ａの接触角の延長線ＬＣ１という。第１軸受３０ａの接触角の延長線ＬＣ１は、基準線ＣＮａに傾斜している。つまり、長線ＬＣ１は、径方向内側に向かうにつれて中心軸ＡＸ方向の第２方向側に位置するように傾斜し、延長線ＬＣ１と基準線ＣＮａとの成す接触角がθ１となっている。 The rolling elements 35a and 35b are balls. The rolling element 35a is arranged between the outer ring 31a and the inner ring 33a, and is in contact with the outer ring raceway surface 31c of the outer ring 31a and the inner ring raceway surface 33c of the inner ring 33a. A virtual line orthogonal to the central axis AX and passing through the center C1 of the rolling element 35a is referred to as a reference line CNa. The extension line of the virtual line connecting the contact point P1 between the rolling element 35a and the outer ring raceway surface 31c and the contact point P2 between the rolling element 35a and the inner ring raceway surface 33c is referred to as an extension line LC1 of the contact angle of the first bearing 30a. The extension line LC1 of the contact angle of the first bearing 30a is inclined to the reference line CNa. That is, the long line LC1 is inclined so as to be located on the second direction side in the central axis AX direction toward the inner side in the radial direction, and the contact angle formed by the extension line LC1 and the reference line CNa is θ1.

転動体３５ｂは、外輪３１ｂと内輪３３ｂとの間に配置され、外輪３１ｂの外輪軌道面３１ｄと内輪３３ｂの内輪軌道面３３ｄとに接触している。なお、軸ＡＸに直交し、かつ、転動体３５ｂの中心Ｃ２を通る仮想線を基準線ＣＮｂという。転動体３５ｂと外輪軌道面３１ｄとの接点Ｐ３と、転動体３５ｂと内輪軌道面３３ｄとの接点Ｐ４と、を結ぶ仮想線の延長線を第２軸受３０ｂの接触角の延長線ＬＣ２という。第２軸受３０ｂの接触角の延長線ＬＣ２は、基準線ＣＮａに傾斜している。つまり、延長線ＬＣ２は、径方向内側に向かうにつれて中心軸ＡＸ方向の第１方向側に位置するように傾斜し、延長線ＬＣ２と基準線ＣＮｂとの成す接触角がθ２となっている。 The rolling element 35b is arranged between the outer ring 31b and the inner ring 33b, and is in contact with the outer ring raceway surface 31d of the outer ring 31b and the inner ring raceway surface 33d of the inner ring 33b. A virtual line orthogonal to the axis AX and passing through the center C2 of the rolling element 35b is referred to as a reference line CNb. The extension line of the virtual line connecting the contact point P3 between the rolling element 35b and the outer ring raceway surface 31d and the contact point P4 between the rolling element 35b and the inner ring raceway surface 33d is referred to as an extension line LC2 of the contact angle of the second bearing 30b. The extension line LC2 of the contact angle of the second bearing 30b is inclined to the reference line CNa. That is, the extension line LC2 is inclined so as to be located on the first direction side in the central axis AX direction toward the inside in the radial direction, and the contact angle formed by the extension line LC2 and the reference line CNb is θ2.

このような正面組合せの構成により、第１軸受３０ａの接触角の延長線ＬＣ１と、第２軸受３０ｂの接触角の延長線ＬＣ２とは、中心軸ＡＸに近づくにつれて互いに近接している。つまり、第１軸受３０ａの接触角の延長線ＬＣ１と中心軸ＡＸとの第１交点ＬＡ１（第１軸受３０ａの作用点）と、第２軸受３０ｂの接触角の延長線ＬＣ２と中心軸ＡＸとの第２交点ＬＡ２（第２軸受３０ｂの作用点）と、の距離は、背面組合せで配置された場合よりも短い。つまり、第１軸受３０ａ及び第２軸受３０ｂは、モーメント荷重に対する剛性が低い。 With such a frontal combination configuration, the extension line LC1 of the contact angle of the first bearing 30a and the extension line LC2 of the contact angle of the second bearing 30b are closer to each other as they approach the central axis AX. That is, the first intersection LA1 (the point of action of the first bearing 30a) between the extension line LC1 of the contact angle of the first bearing 30a and the central axis AX, and the extension line LC2 and the central axis AX of the contact angle of the second bearing 30b. The distance between the second intersection LA2 (the point of action of the second bearing 30b) and the second intersection LA2 (the point of action of the second bearing 30b) is shorter than when the bearings are arranged in the back combination. That is, the first bearing 30a and the second bearing 30b have low rigidity with respect to a moment load.

また、本実施形態では、第１軸受３０ａの接触角の延長線ＬＣ１と中心軸ＡＸとの第１交点ＬＡ１と、第２軸受３０ｂの接触角の延長線ＬＣ２と中心軸ＡＸとの第２交点ＬＡ２とは、一致している。つまり、中心軸ＡＸ上において、第１交点ＬＡ１と第２交点ＬＡ２との作用点間距離がゼロとなっている。この構成により、第１軸受３０ａ及び第２軸受３０ｂは、ボールねじ装置１０を実質的に１点の交点ＬＡＸで支持する。このため、第１軸受３０ａ及び第２軸受３０ｂは、モーメント荷重に対する剛性がさらに小さくなっている。よって、車両の走行中、第１軸受３０ａ及び第２軸受３０ｂにモーメント荷重が入力しても、反作用としてボールねじ装置１０に入力されるモーメント荷重は大きく低減する。これにより、モーメント荷重の入力によってボールねじ装置１０に異音が発生する、ということが抑止される。 Further, in the present embodiment, the first intersection LA1 between the extension line LC1 of the contact angle of the first bearing 30a and the central axis AX, and the second intersection of the extension line LC2 of the contact angle of the second bearing 30b and the central axis AX. It is in agreement with LA2. That is, on the central axis AX, the distance between the action points of the first intersection LA1 and the second intersection LA2 is zero. With this configuration, the first bearing 30a and the second bearing 30b support the ball screw device 10 at substantially one intersection point LAX. Therefore, the rigidity of the first bearing 30a and the second bearing 30b with respect to the moment load is further reduced. Therefore, even if the moment load is input to the first bearing 30a and the second bearing 30b while the vehicle is running, the moment load input to the ball screw device 10 as a reaction is greatly reduced. As a result, it is possible to prevent the ball screw device 10 from generating an abnormal noise due to the input of the moment load.

また、従動プーリ２３の外周面２３ａにおける中心軸ＡＸ方向の中央２３ｆを通り、かつナット１３の中心軸ＡＸと直交する仮想線ＣＮは、中心軸ＡＸ上で、第１交点ＬＡ１と第２交点ＬＡ２の間を通る。本実施形態では、第１交点ＬＡ１と第２交点ＬＡ２中心軸ＡＸ上で一致しているため、仮想線ＣＮは、中心軸ＡＸ上で第１交点ＬＡ１と第２交点ＬＡ２の両方を通る。これにより、第１軸受３０ａ及び第２軸受３０ｂの支点（交点ＬＡＸ）と、ベルト２５の張力による力点は、中心軸ＡＸ上で一致する。よって、ナット１３にベルト２５の張力が作用してもモーメント荷重が発生しない。 Further, the virtual line CN that passes through the center 23f in the central axis AX direction on the outer peripheral surface 23a of the driven pulley 23 and is orthogonal to the central axis AX of the nut 13 is the first intersection LA1 and the second intersection LA2 on the central axis AX. Pass between. In the present embodiment, since the first intersection LA1 and the second intersection LA2 coincide with each other on the central axis AX, the virtual line CN passes through both the first intersection LA1 and the second intersection LA2 on the central axis AX. As a result, the fulcrum (intersection point LAX) of the first bearing 30a and the second bearing 30b and the force point due to the tension of the belt 25 coincide with each other on the central axis AX. Therefore, even if the tension of the belt 25 acts on the nut 13, no moment load is generated.

予圧付与部材４０ａ、４０ｂは、弾性体により構成され、中心軸ＡＸを中心とする環状のゴムである。予圧付与部材４０ａは、第１軸受３０ａの外輪３１ａと第２本体１０３の段差面１０３ａの間に配置されている。予圧付与部材４０ｂは、第２軸受３０ｂの外輪３１ｂと、第１本体１０１の段差面１０１ａとの間に配置されている。また、予圧付与部材４０ａ、４０ｂのそれぞれは、ハウジング１００内に組み付けられて中心軸ＡＸ方向に圧縮荷重を受けており、第１軸受３０ａ及び第２軸受３０ｂの外輪３１ａ、３１ｂを押圧している。 The preload applying members 40a and 40b are made of elastic bodies and are annular rubbers centered on the central axis AX. The preload applying member 40a is arranged between the outer ring 31a of the first bearing 30a and the stepped surface 103a of the second main body 103. The preload applying member 40b is arranged between the outer ring 31b of the second bearing 30b and the stepped surface 101a of the first main body 101. Further, each of the preload applying members 40a and 40b is assembled in the housing 100 and receives a compressive load in the direction of the central axis AX, and presses the outer rings 31a and 31b of the first bearing 30a and the second bearing 30b. ..

予圧付与部材４０ａ、４０ｂは、第１軸受３０ａ及び第２軸受３０ｂの中心軸ＡＸ方向の両側に配置されている。そして、第１軸受３０ａ及び第２軸受３０ｂは、中心軸ＡＸ方向に沿って変位可能である。これにより、第２本体１０３の段差面１０３ａと第１本体１０１と段差面１０１ａとにおける中心軸ＡＸ方向の距離が所定の長さとなっていない場合、言い換えると、ハウジング１００の第１本体１０１と第２本体１０３に製造誤差がある場合、その誤差分を予圧付与部材４０ａ、４０ｂが吸収する。よって、ハウジング１００の第１本体１０１と第２本体１０３とに製造誤差があったとしても、第１軸受３０ａ及び第２軸受３０ｂの予圧量が変動しない。また、ラック８８ｂに対して中心軸ＡＸ方向に大きな衝撃荷重が作用した場合、その衝撃荷重を予圧付与部材４０ａ、４０ｂが吸収する。また、予圧付与部材４０ａ、４０ｂによって、ボールねじ装置１０の周辺において中心軸ＡＸ方向の振動が抑制され、いわゆるラトル音が低減する。 The preload applying members 40a and 40b are arranged on both sides of the first bearing 30a and the second bearing 30b in the central axis AX direction. The first bearing 30a and the second bearing 30b can be displaced along the central axis AX direction. As a result, if the distance between the stepped surface 103a of the second main body 103, the first main body 101, and the stepped surface 101a in the central axis AX direction is not a predetermined length, in other words, the first main body 101 and the first main body 101 of the housing 100 and the first main body 101. 2 If there is a manufacturing error in the main body 103, the preload applying members 40a and 40b absorb the error. Therefore, even if there is a manufacturing error between the first main body 101 and the second main body 103 of the housing 100, the preload amounts of the first bearing 30a and the second bearing 30b do not fluctuate. Further, when a large impact load acts on the rack 88b in the direction of the central axis AX, the preload applying members 40a and 40b absorb the impact load. Further, the preload applying members 40a and 40b suppress the vibration in the central axis AX direction around the ball screw device 10, and the so-called rattle noise is reduced.

以上で説明したように、動力伝達装置１は、ハウジング１００と、ハウジング１００に収容されるナット１３、ナット１３を貫通するねじ軸１１、及びナット１３とねじ軸１１との間に配置される複数のボール１５を有するボールねじ装置１０と、動力源から動力が伝達されて駆動する駆動プーリ２１、ナット１３に固定される従動プーリ２３、及び駆動プーリ２１と従動プーリ２３の外周面に巻き掛けられるベルト２５を有するプーリ装置２０と、ハウジング１００とナット１３との間に設けられ、ナット１３の中心軸ＡＸに平行な中心軸ＡＸ方向に並ぶ第１軸受３０ａ及び第２軸受３０ｂと、を備える。第１軸受３０ａ及び第２軸受３０ｂは、正面組合せとなるように配置される。つまり、第１軸受３０ａ及び第２軸受３０ｂは、作用点間距離が小さい正面組合せとなっている。よって、第１軸受３０ａ及び第２軸受３０ｂによるモーメント荷重に対する剛性が低い。これにより、ボールねじ装置１０に入力されるモーメント荷重が低減し、異音の発生が抑制される。 As described above, the power transmission device 1 includes the housing 100, the nut 13 housed in the housing 100, the screw shaft 11 penetrating the nut 13, and a plurality of power transmission devices 1 arranged between the nut 13 and the screw shaft 11. The ball screw device 10 having the ball 15 and the drive pulley 21 driven by transmitting power from the power source, the driven pulley 23 fixed to the nut 13, and the drive pulley 21 and the driven pulley 23 are wound around the outer peripheral surfaces. A pulley device 20 having a belt 25 and a first bearing 30a and a second bearing 30b provided between the housing 100 and the nut 13 and arranged in the direction of the central axis AX parallel to the central axis AX of the nut 13 are provided. The first bearing 30a and the second bearing 30b are arranged so as to form a frontal combination. That is, the first bearing 30a and the second bearing 30b are in a frontal combination in which the distance between the working points is small. Therefore, the rigidity of the first bearing 30a and the second bearing 30b with respect to the moment load is low. As a result, the moment load input to the ball screw device 10 is reduced, and the generation of abnormal noise is suppressed.

また、動力伝達装置１において、第１軸受３０ａ及び第２軸受３０ｂは、従動プーリ２３の両側にそれぞれ配置されている。言い換えると、第１軸受３０ａ及び第２軸受３０ｂは、それぞれ従動プーリ２３に隣り合うように配置されて中心軸ＡＸ方向の両側から隙間Ｓ１、Ｓ２を介して従動プーリ２３を挟む。従動プーリ２３の外周面２３ａの中心軸ＡＸ方向の中央２３ｆを通り、かつナット１３の中心軸ＡＸと直交する仮想線ＣＮは、第１軸受３０ａの接触角の延長線ＬＣ１とナット１３の中心軸ＡＸとが交わる第１交点ＬＡ１と、第２軸受３０ｂの接触角の延長線ＬＣ２とナット１３の中心軸ＡＸとが交わる第２交点ＬＡ２と、の間を通る。ナット１３は、第１交点ＬＡ１と第２交点ＬＡ２との２点で支持されているところ、上記構成により、ベルト２５の張力による荷重が２点の間に収まる。よって、ベルト２５の張力によるモーメント荷重が低減する。 Further, in the power transmission device 1, the first bearing 30a and the second bearing 30b are arranged on both sides of the driven pulley 23, respectively. In other words, the first bearing 30a and the second bearing 30b are arranged adjacent to the driven pulley 23, respectively, and sandwich the driven pulley 23 from both sides in the central axis AX direction via gaps S1 and S2. The virtual line CN that passes through the center 23f of the outer peripheral surface 23a of the driven pulley 23 in the central axis AX direction and is orthogonal to the central axis AX of the nut 13 is an extension line LC1 of the contact angle of the first bearing 30a and the central axis of the nut 13. It passes between the first intersection LA1 where the AX intersects and the second intersection LA2 where the extension line LC2 of the contact angle of the second bearing 30b and the central axis AX of the nut 13 intersect. The nut 13 is supported at two points, the first intersection LA1 and the second intersection LA2, and the load due to the tension of the belt 25 is contained between the two points by the above configuration. Therefore, the moment load due to the tension of the belt 25 is reduced.

また、動力伝達装置１において、第１軸受３０ａの接触角の延長線ＬＣ１とナット１３の中心軸ＡＸとが交わる第１交点ＬＡ１と、第２軸受３０ｂの接触角の延長線ＬＣ２とナット１３の中心軸ＡＸとが交わる第２交点ＬＡ２は、ナット１３の中心軸ＡＸ上で一致する。そして、従動プーリ２３の外周面２３ａの中心軸ＡＸ方向の中央２３ｆを通り、かつナット１３の中心軸ＡＸと直交する仮想線ＣＮは、第１交点ＬＡ１と第２交点ＬＡ２との中央を通る。これにより、ナット１３にベルト２５の張力が作用してもモーメント荷重が発生しない。 Further, in the power transmission device 1, the first intersection LA1 where the extension line LC1 of the contact angle of the first bearing 30a and the central axis AX of the nut 13 intersect, and the extension line LC2 and the nut 13 of the contact angle of the second bearing 30b. The second intersection LA2 where the central axis AX intersects coincides with the central axis AX of the nut 13. Then, the virtual line CN passing through the center 23f of the outer peripheral surface 23a of the driven pulley 23 in the central axis AX direction and orthogonal to the central axis AX of the nut 13 passes through the center of the first intersection LA1 and the second intersection LA2. As a result, no moment load is generated even if the tension of the belt 25 acts on the nut 13.

また、動力伝達装置１において、第１軸受３０ａ及び第２軸受３０ｂに予圧を与える予圧付与部材４０ａ、４０ｂを備える。第１軸受３０ａ及び第２軸受３０ｂのそれぞれは、ハウジング１００に嵌め合わされる外輪３１ａ、３１ｂを含む。外輪３１ａ、３１ｂは、予圧付与部材４０ａ、４０ｂによって従動プーリ２３に向かって押圧されるとともに、従動プーリ２３と離隔して従動プーリ２３との間に隙間Ｓ１、Ｓ２が形成されている。これにより、外輪３１ａ、３１ｂに中心軸ＡＸ方向の寸法誤差があると、従動プーリ２３との隙間Ｓ１、Ｓ２が変化したり、又は予圧付与部材４０ａ、４０ｂが変形したりして、寸法誤差が吸収される。よって、外輪軌道面３１ｃ、３１ｄは中心軸ＡＸ方向に変位せず、転動体３５ａ、３５ｂに作用する荷重は、予圧付与部材４０ａ、４０ｂの押圧による荷重のみとなる。この結果、所定の予圧量となり、軸受トルクの安定化が図れる。 Further, the power transmission device 1 includes preload applying members 40a and 40b that preload the first bearing 30a and the second bearing 30b. Each of the first bearing 30a and the second bearing 30b includes outer rings 31a and 31b fitted to the housing 100. The outer rings 31a and 31b are pressed toward the driven pulley 23 by the preload applying members 40a and 40b, and gaps S1 and S2 are formed between the driven pulley 23 and the driven pulley 23. As a result, if the outer rings 31a and 31b have a dimensional error in the central axis AX direction, the gaps S1 and S2 with the driven pulley 23 may change, or the preload applying members 40a and 40b may be deformed, resulting in a dimensional error. Be absorbed. Therefore, the outer ring raceway surfaces 31c and 31d are not displaced in the central axis AX direction, and the load acting on the rolling elements 35a and 35b is only the load due to the pressing of the preload applying members 40a and 40b. As a result, a predetermined preload amount is obtained, and the bearing torque can be stabilized.

また、動力伝達装置１において、ナット１３の外周面には、硬化処理されて転動体３５ａ、３５ｂが転動する内輪軌道面３３ｃ、３３ｄが２つ形成されている。これにより、内輪３３ａ、３３ｂが不要となり、動力伝達装置１を径方向に小型化することができる。また、内輪３３ａ、３３ｂは、隣接する従動プーリ２３から中心軸ＡＸ方向の荷重を受けたとしても変位しない。つまり、従動プーリ２３が後述する実施形態２や変形例３で示すように、ナット１３と別体の場合、ベルト２５の振動を受けて中心軸ＡＸ方向に位置ずれするような荷重を受け、従動プーリ２３が内輪３３ａ、３３ｂを押圧する可能性がある。仮に内輪３３ａ、３３ｂが移動すると、内輪３３ａ、３３ｂの内輪軌道面３３ｃ、３３ｄに接触する転動体３５ａ、３５ｂを押圧する押圧量が増加し、軸受トルクが増大してしまう。従って、本実施形態では、内輪３３ａ、３３ｂによる中心軸ＡＸ方向の移動を規制して、軸受トルクが増大することを回避している。 Further, in the power transmission device 1, two inner ring raceway surfaces 33c and 33d, which are hardened and roll the rolling elements 35a and 35b, are formed on the outer peripheral surface of the nut 13. As a result, the inner rings 33a and 33b are not required, and the power transmission device 1 can be miniaturized in the radial direction. Further, the inner rings 33a and 33b do not displace even if a load in the central axis AX direction is received from the adjacent driven pulley 23. That is, as shown in the second embodiment and the third modification described later, when the driven pulley 23 is separate from the nut 13, it receives a load that causes the belt 25 to be displaced in the central axis AX direction and is driven. The pulley 23 may press the inner rings 33a and 33b. If the inner rings 33a and 33b move, the amount of pressure that presses the rolling elements 35a and 35b that come into contact with the inner ring raceway surfaces 33c and 33d of the inner rings 33a and 33b increases, and the bearing torque increases. Therefore, in the present embodiment, the movement of the inner rings 33a and 33b in the central axis AX direction is restricted to prevent the bearing torque from increasing.

また、動力伝達装置１において、従動プーリ２３は、ナット１３と同じ金属材料で一体成形されている。これにより、部品点数が低減し、組み付け工数が削減する。また、従動プーリ２３は、ナット１３に対して周方向に位置ずれしない。よって、従動プーリ２３がナット１３に対して空転して動力が伝達されない、ということを回避できる。また、従動プーリ２３は、ナット１３に対し中心軸ＡＸ方向に位置ずれしない。よって、従動プーリ２３が中心軸ＡＸ方向に移動して外輪３１ａ、３１ｂに接触して予圧量が変化する、ということを回避できる。また、上記構成によれば、内輪３３ａ、３３ｂがナット１３と別体で形成されている場合、従動プーリ２３が内輪３３ａ、３３ｂを押圧して軸受トルクが増大してしまう、ということを回避できる。 Further, in the power transmission device 1, the driven pulley 23 is integrally molded with the same metal material as the nut 13. As a result, the number of parts is reduced and the assembly man-hours are reduced. Further, the driven pulley 23 does not shift in the circumferential direction with respect to the nut 13. Therefore, it is possible to avoid that the driven pulley 23 idles with respect to the nut 13 and the power is not transmitted. Further, the driven pulley 23 does not shift in the central axis AX direction with respect to the nut 13. Therefore, it is possible to avoid that the driven pulley 23 moves in the direction of the central axis AX and comes into contact with the outer rings 31a and 31b to change the preload amount. Further, according to the above configuration, when the inner rings 33a and 33b are formed separately from the nut 13, it is possible to avoid that the driven pulley 23 presses the inner rings 33a and 33b to increase the bearing torque. ..

また、動力伝達装置において、第１軸受３０ａ及び第２軸受３０ｂの両側に予圧付与部材４０ａ、４０ｂが配置されている。これにより、ハウジング１００の中心軸ＡＸ方向の製造誤差を予圧付与部材４０ａ、４０ｂが吸収し、予圧量が変動することが防止される。 Further, in the power transmission device, preload applying members 40a and 40b are arranged on both sides of the first bearing 30a and the second bearing 30b. As a result, the preload applying members 40a and 40b absorb the manufacturing error in the central axis AX direction of the housing 100, and the preload amount is prevented from fluctuating.

（変形例１）
図６は、変形例１の動力伝達装置の断面図である。なお、以下の説明においては、上述した実施形態で説明したものと同じ構成要素には同一の符号を付して重複する説明は省略する。 (Modification example 1)
FIG. 6 is a cross-sectional view of the power transmission device of the first modification. In the following description, the same components as those described in the above-described embodiment will be designated by the same reference numerals, and duplicate description will be omitted.

変形例１の動力伝達装置１Ａは、以下の点で実施形態１の動力伝達装置１と相違する。
変形例１の動力伝達装置１Ａにおいて、第１軸受３０ａの接触角の延長線ＬＣ３と基準線ＣＮａとの成す接触角がθ３となっている。変形例１の動力伝達装置１Ａにおいて、第２軸受３０ｂの接触角の延長線ＬＣ４と基準線ＣＮｂとの成す接触角がθ４となっている。 The power transmission device 1A of the first modification is different from the power transmission device 1 of the first embodiment in the following points.
In the power transmission device 1A of the first modification, the contact angle formed by the extension line LC3 of the contact angle of the first bearing 30a and the reference line CNa is θ3. In the power transmission device 1A of the first modification, the contact angle formed by the extension line LC4 of the contact angle of the second bearing 30b and the reference line CNb is θ4.

具体的には、第１軸受３０ａの接触角の延長線ＬＣ３と基準線ＣＮａとの成す接触角θ３は、実施形態１の接触角θ１よりも小さい。また、第２軸受３０ｂの接触角の延長線ＬＣ４と基準線ＣＮｂとの成す接触角θ４は、実施形態１の接触角θ２よりも小さい。これにより、第１軸受３０ａの接触角の延長線ＬＣ３と、第２軸受３０ｂの接触角の延長線ＬＣ４とは、転動体３５ａ、３５ｂの中心Ｃ１、Ｃ２から中心軸ＡＸに近づくにつれて互いに近接するものの、中心軸ＡＸに到達する前に互いに交差しない。よって、第１軸受３０ａ、第２軸受３０ｂは、ボールねじ装置を第１交点ＬＡ３（第１軸受３０ａの作用点）と第２交点ＬＡ４（第２軸受３０ｂの作用点）の２点で支持する。そして、このような例によっても、作用点間距離（第１交点ＬＡ３と第２交点ＬＡ４との距離）は、背面組合せの場合よりも短く、モーメント荷重に対する剛性が低い。 Specifically, the contact angle θ3 formed by the extension line LC3 of the contact angle of the first bearing 30a and the reference line CNa is smaller than the contact angle θ1 of the first embodiment. Further, the contact angle θ4 formed by the extension line LC4 of the contact angle of the second bearing 30b and the reference line CNb is smaller than the contact angle θ2 of the first embodiment. As a result, the extension line LC3 of the contact angle of the first bearing 30a and the extension line LC4 of the contact angle of the second bearing 30b come closer to each other as they approach the central axis AX from the centers C1 and C2 of the rolling elements 35a and 35b. However, they do not intersect each other before reaching the central axis AX. Therefore, the first bearing 30a and the second bearing 30b support the ball screw device at two points, the first intersection LA3 (the point of action of the first bearing 30a) and the second intersection LA4 (the point of action of the second bearing 30b). .. Even in such an example, the distance between the points of action (the distance between the first intersection LA3 and the second intersection LA4) is shorter than that in the case of the back surface combination, and the rigidity against the moment load is low.

また、従動プーリ２３の外周面２３ａの中心軸ＡＸ方向の中央２３ｆを通り、かつナット１３の中心軸ＡＸと直交する仮想線ＣＮは、第１交点ＬＡ３と第２交点ＬＡ４との中央を通る。これにより、第１軸受３０ａ及び第２軸受３０ｂの各作用点と、ベルト２５の張力の力点との距離が同等である。よって、ベルト２５の張力によってナット１３に生じるモーメント荷重が極めて小さい。また、第１交点ＬＡ３と第２交点ＬＡ４との中央を仮想線ＣＮが通ることにより、ベルト２５の張力による荷重は、第１軸受３０ａ及び第２軸受３０ｂに均等に作用する。 Further, the virtual line CN passing through the center 23f of the outer peripheral surface 23a of the driven pulley 23 in the central axis AX direction and orthogonal to the central axis AX of the nut 13 passes through the center of the first intersection LA3 and the second intersection LA4. As a result, the distances between the points of action of the first bearing 30a and the second bearing 30b and the points of tension of the belt 25 are the same. Therefore, the moment load generated in the nut 13 due to the tension of the belt 25 is extremely small. Further, since the virtual line CN passes through the center of the first intersection LA3 and the second intersection LA4, the load due to the tension of the belt 25 acts evenly on the first bearing 30a and the second bearing 30b.

以上で説明したように、動力伝達装置１Ａの仮想線ＣＮは、第１交点ＬＡ１と第２交点ＬＡ２との中央を通る。これにより、ベルト２５の張力による荷重が第１軸受３０ａ又は第２軸受３０ｂに偏ることがなく、第１軸受３０ａ及び第２軸受３０ｂの耐久性が向上する。 As described above, the virtual line CN of the power transmission device 1A passes through the center of the first intersection LA1 and the second intersection LA2. As a result, the load due to the tension of the belt 25 is not biased to the first bearing 30a or the second bearing 30b, and the durability of the first bearing 30a and the second bearing 30b is improved.

（変形例２）
図７は、変形例２の動力伝達装置の断面図である。変形例２の動力伝達装置１Ｂは、第２軸受３０ｂと従動プーリ２３との距離が大きく、隙間Ｓ２が拡大している点が変形例１の動力伝達装置１Ａと相違する。 (Modification 2)
FIG. 7 is a cross-sectional view of the power transmission device of the second modification. The power transmission device 1B of the second modification is different from the power transmission device 1A of the first modification in that the distance between the second bearing 30b and the driven pulley 23 is large and the gap S2 is expanded.

これにより、第２軸受３０ｂの接触角の延長線ＬＣ４は、変形例１よりも第２方向側寄りに移動している。そして、従動プーリ２３の外周面２３ａの中心軸ＡＸ方向の中央２３ｆを通り、かつナット１３の中心軸ＡＸと直交する仮想線ＣＮは、第１交点ＬＡ３と第２交点ＬＡ４との中央ではなく、第１交点ＬＡ３寄りとなっている。 As a result, the extension line LC4 of the contact angle of the second bearing 30b is moved closer to the second direction side than the modification 1. The virtual line CN that passes through the center 23f of the outer peripheral surface 23a of the driven pulley 23 in the central axis AX direction and is orthogonal to the central axis AX of the nut 13 is not the center of the first intersection LA3 and the second intersection LA4. It is closer to the first intersection LA3.

以上で説明したように、動力伝達装置１Ｂは、第１軸受３０ａの接触角の延長線ＬＣ３とナット１３の中心軸ＡＸとが交わる第３交点ＬＡ３と、第２軸受３０ｂの接触角の延長線ＬＣ４とナット１３の中心軸ＡＸとが交わる第４交点ＬＡ４と、の間を通る。これにより、第１軸受３０ａ及び第２軸受３０ｂの各作用点とベルト２５の張力の力点との距離はほぼ同等であり、ベルト２５の張力によってナット１３に発生するモーメント荷重は極めて小さい。 As described above, in the power transmission device 1B, the extension line LC3 of the contact angle of the first bearing 30a and the extension line of the contact angle of the second bearing 30b and the third intersection LA3 where the central axis AX of the nut 13 intersects. It passes between the fourth intersection LA4, where the LC4 and the central axis AX of the nut 13 intersect. As a result, the distances between the points of action of the first bearing 30a and the second bearing 30b and the points of tension of the belt 25 are almost the same, and the moment load generated in the nut 13 by the tension of the belt 25 is extremely small.

（実施形態２）
図８は、実施形態２の動力伝達装置の断面図である。実施形態２の動力伝達装置１Ｃは、金属材料で一体形成されたナット１３及び従動プーリ２３に代えて、金属材料で形成されたナット１３Ａと樹脂材料で形成された従動プーリ２３Ａを備える点で、実施形態１の動力伝達装置１と相違する。 (Embodiment 2)
FIG. 8 is a cross-sectional view of the power transmission device of the second embodiment. The power transmission device 1C of the second embodiment includes a nut 13A made of a metal material and a driven pulley 23A made of a resin material instead of the nut 13 and the driven pulley 23 integrally formed of the metal material. It is different from the power transmission device 1 of the first embodiment.

従動プーリ２３Ａは、ボールねじ装置１０Ａにおけるナット１３Ａの外周面１３ａに嵌合する。従動プーリ２３Ａの第１端面はナット１３Ａの壁部１３ｂに接する。従動プーリ２３Ａの第２端面は位置決め部材１７に接する。従動プーリ２３Ａは、位置決め部材１７及び壁部１３ｂによって、中心軸ＡＸ方向に位置決めされる。位置決め部材１７は、ロックナットと呼ばれる。 The driven pulley 23A fits on the outer peripheral surface 13a of the nut 13A in the ball screw device 10A. The first end surface of the driven pulley 23A is in contact with the wall portion 13b of the nut 13A. The second end surface of the driven pulley 23A is in contact with the positioning member 17. The driven pulley 23A is positioned in the central axis AX direction by the positioning member 17 and the wall portion 13b. The positioning member 17 is called a locknut.

上記構成によれば、中心軸ＡＸ方向の荷重を受けるナット１３Ａを金属材料で形成し、従動プーリ２３Ａを軽量な樹脂材料で形成している。よって、動力伝達装置１Ｃの剛性や耐久性を維持しながら、軽量化を図っている。 According to the above configuration, the nut 13A that receives the load in the central axis AX direction is formed of a metal material, and the driven pulley 23A is formed of a lightweight resin material. Therefore, the weight is reduced while maintaining the rigidity and durability of the power transmission device 1C.

（変形例３）
図９は、変形例３の動力伝達装置の断面図である。図１０は、変形例３のナットの一部を拡大し、かつ斜視した斜視図である。変形例３の動力伝達装置１Ｄは、金属材料で形成されたナット１３Ｂと、樹脂材料で形成された従動プーリ２３Ｂとをインサート成型により一体化している点で、実施形態２の動力伝達装置１Ｃと相違する。 (Modification example 3)
FIG. 9 is a cross-sectional view of the power transmission device of the modified example 3. FIG. 10 is an enlarged and perspective view of a part of the nut of the modified example 3. The power transmission device 1D of the third modification is the power transmission device 1C of the second embodiment in that the nut 13B made of a metal material and the driven pulley 23B made of a resin material are integrated by insert molding. It's different.

図９、図１０に示すように、ナット１３Ｂの外周面１３ａには、径方向内側に窪み、かつ周方向に延在する溝部１３ｃが形成されている。溝部１３ｃの底面には、径方向外側に突出する一対の突起１３ｄ、１３ｅが形成されている。一対の突起１３ｄ、１３ｅは、互いに中心軸ＡＸ方向に離隔している。また、一対の突起１３ｄ、１３ｅは、周方向に複数形成されている。突起１３ｄは、周方向に隣り合う突起１３ｄに対し、離隔している。突起１３ｅは、周方向に隣り合う突起１３ｅに対し、離隔している。これにより、金型にナット１３Ｂをインサートさせて樹脂材料を成型した場合、硬化した樹脂、つまり、従動プーリ２３Ｂの一部は、一対の突起１３ｄ、１３ｅの間や、突起１３ｄ同士の間や、突起１３ｅ同士の間に入りこむ。よって、一対の突起１３ｄ、１３ｅは、従動プーリ２３Ｂ内に埋設される。 As shown in FIGS. 9 and 10, a groove portion 13c that is recessed inward in the radial direction and extends in the circumferential direction is formed on the outer peripheral surface 13a of the nut 13B. A pair of protrusions 13d and 13e protruding outward in the radial direction are formed on the bottom surface of the groove portion 13c. The pair of protrusions 13d and 13e are separated from each other in the central axis AX direction. Further, a plurality of the pair of protrusions 13d and 13e are formed in the circumferential direction. The protrusions 13d are separated from the protrusions 13d adjacent to each other in the circumferential direction. The protrusions 13e are separated from the protrusions 13e adjacent to each other in the circumferential direction. As a result, when the nut 13B is inserted into the mold to mold the resin material, the cured resin, that is, a part of the driven pulley 23B, is placed between the pair of protrusions 13d and 13e, between the protrusions 13d, and so on. It gets in between the protrusions 13e. Therefore, the pair of protrusions 13d and 13e are embedded in the driven pulley 23B.

以上説明したように、動力伝達装置１Ｄにおいて、ナット１３Ｂの外周面１３ａには、径方向内側に窪む溝部１３ｃが形成され、従動プーリ２３Ｂは、樹脂製であり、インサート成型によりナット１３Ｂと一体化され、従動プーリ２３Ｂは、一部が溝部１３Ｃに入り込んでいる。従動プーリ２３Ｂの中心軸ＡＸ方向の移動を規制できる。よって、従動プーリ２３Ｂが第１軸受３０ａ及び第２軸受３０ｂに接触して予圧量が変更することを回避できる。また、溝部１３ｃ内において、従動プーリ２３Ｂの一部は、周方向に隣接する突起１３ｄ及び１３ｅの間に入り込んでいる。これにより、従動プーリ２３Ｂは、ナット１３Ｂに対して、相対回転することが規制される。従って、従動プーリ２３Ｂの回転運動を確実にナット１３Ｂに伝達することができる。 As described above, in the power transmission device 1D, the outer peripheral surface 13a of the nut 13B is formed with a groove portion 13c recessed inward in the radial direction, and the driven pulley 23B is made of resin and is integrated with the nut 13B by insert molding. The driven pulley 23B is partially inserted into the groove portion 13C. The movement of the driven pulley 23B in the central axis AX direction can be regulated. Therefore, it is possible to prevent the driven pulley 23B from coming into contact with the first bearing 30a and the second bearing 30b and changing the preload amount. Further, in the groove portion 13c, a part of the driven pulley 23B is inserted between the protrusions 13d and 13e adjacent to each other in the circumferential direction. As a result, the driven pulley 23B is restricted from rotating relative to the nut 13B. Therefore, the rotational movement of the driven pulley 23B can be reliably transmitted to the nut 13B.

（実施形態３）
図１１は、実施形態３の動力伝達装置の断面図である。実施形態３の動力伝達装置１Ｅは、以下の点で実施形態１の動力伝達装置１と相違する。実施形態３の動力伝達装置１Ｅは、第１軸受３０ａ及び第２軸受３０ｂにおいて、外輪３１ａ、３１ｂの外周面にグリス用溝３６ａ、３６ｂ（図４参照）が形成されていない代わりに、周方向に延在する凹部３６ｃ、３６ｄがそれぞれ形成されている。外輪３１ａと第２本体１０３の内周面１０３ｂとの間に、弾性部材５０ａが介在している。外輪３１ｂと第１本体１０１の内周面１０１ｂとの間に、弾性部材５０ｂが介在している。 (Embodiment 3)
FIG. 11 is a cross-sectional view of the power transmission device of the third embodiment. The power transmission device 1E of the third embodiment is different from the power transmission device 1 of the first embodiment in the following points. In the power transmission device 1E of the third embodiment, in the first bearing 30a and the second bearing 30b, the grease grooves 36a and 36b (see FIG. 4) are not formed on the outer peripheral surfaces of the outer rings 31a and 31b, but in the circumferential direction. Recesses 36c and 36d extending to the above are formed, respectively. An elastic member 50a is interposed between the outer ring 31a and the inner peripheral surface 103b of the second main body 103. An elastic member 50b is interposed between the outer ring 31b and the inner peripheral surface 101b of the first main body 101.

凹部３６ｃ、３６ｄは、弾性部材５０ａ、５０ｂを収容するための溝である。これにより、外輪３１ａ、３１ｂが中心軸ＡＸ方向に摺動すると、弾性部材５０ａ、５０ｂは、外輪３１ａ、３１ｂと共に中心軸ＡＸ方向に変位する。また、弾性部材５０ａ、５０ｂは、断面形状が円形のＯリングである。弾性部材５０ａ、５０ｂの外周部は、外輪３１ａ、３１ｂの外周面よりも径方向外側に突出している。よって、外輪３１ａの凹部３６ｃに収容された弾性部材５０ａは、第２本体１０３の内周面１０３ｂに当接している。また、外輪３１ｂの凹部３６ｄに収容された弾性部材５０ｂは、第１本体１０１の内周面１０１ｂに当接している。 The recesses 36c and 36d are grooves for accommodating the elastic members 50a and 50b. As a result, when the outer rings 31a and 31b slide in the central axis AX direction, the elastic members 50a and 50b are displaced in the central axis AX direction together with the outer rings 31a and 31b. Further, the elastic members 50a and 50b are O-rings having a circular cross-sectional shape. The outer peripheral portions of the elastic members 50a and 50b project radially outward from the outer peripheral surfaces of the outer rings 31a and 31b. Therefore, the elastic member 50a housed in the recess 36c of the outer ring 31a is in contact with the inner peripheral surface 103b of the second main body 103. Further, the elastic member 50b housed in the recess 36d of the outer ring 31b is in contact with the inner peripheral surface 101b of the first main body 101.

以上で説明したように、動力伝達装置１Ｅにおいて、外輪３１ａ、３１ｂの外周面とハウジング１００との間に、弾性部材５０ａ、５０ｂが介在している。これにより、ボールねじ装置１０における径方向の振動が弾性部材５０ａ、５０ｂに吸収され、いわゆるラトル音の発生が抑制される。なお、本実施形態では、弾性部材５０ａ、５０ｂにＯリングを用いているが、外輪３１ａ、３１ｂの外周側を囲む円筒状の樹脂部材を用いてもよい。これによれば、Ｏリングよりも外輪３１ａ、３１ｂの外周面を多く被覆でき、いわゆるラトル音の発生を確実に抑制することができる。なお、円筒状の樹脂部材を用いる場合には、凹部３６ｃ、３６ｄを形成する必要がない。 As described above, in the power transmission device 1E, the elastic members 50a and 50b are interposed between the outer peripheral surfaces of the outer rings 31a and 31b and the housing 100. As a result, the radial vibration of the ball screw device 10 is absorbed by the elastic members 50a and 50b, and the generation of so-called rattle noise is suppressed. In the present embodiment, the O-ring is used for the elastic members 50a and 50b, but a cylindrical resin member surrounding the outer peripheral side of the outer rings 31a and 31b may be used. According to this, the outer peripheral surfaces of the outer rings 31a and 31b can be covered more than the O-ring, and the generation of so-called rattle noise can be reliably suppressed. When a cylindrical resin member is used, it is not necessary to form the recesses 36c and 36d.

（実施形態４）
図１２は、実施形態４の動力伝達装置の断面図である。実施形態４の動力伝達装置１Ｆは、以下の点で実施形態１の動力伝達装置１と相違する。実施形態４の動力伝達装置１Ｆは、予圧付与部材４０ａ、４０ｂに代えて予圧付与部材４１ａ、４１ｂを備える。さらに第１シール部材６０ａ、６０ｂを備える。外輪３１ａ、３１ｂには、従動プーリ２３側に向かって延出する延出部３７ａ、３７ｂが形成されている。従動プーリ２３の第１側面２３ｄと第２側面２３ｅには、凹部２７ａ、２７ｂが形成されている。 (Embodiment 4)
FIG. 12 is a cross-sectional view of the power transmission device of the fourth embodiment. The power transmission device 1F of the fourth embodiment is different from the power transmission device 1 of the first embodiment in the following points. The power transmission device 1F of the fourth embodiment includes preload applying members 41a and 41b instead of the preload applying members 40a and 40b. Further, the first seal members 60a and 60b are provided. The outer rings 31a and 31b are formed with extending portions 37a and 37b extending toward the driven pulley 23 side. Recesses 27a and 27b are formed on the first side surface 23d and the second side surface 23e of the driven pulley 23.

なお、予圧付与部材４１ａ、４１ｂと、第１シール部材６０ａ、６０ｂと、延出部３７ａ、３７ｂと、凹部２７ａ、２７ｂのそれぞれは、従動プーリ２３を境界として、第１軸受３０ａ側と第２軸受３０ｂ側に分かれて配置されている。予圧付与部材４１ａ、４１ｂと、第１シール部材６０ａ、６０ｂと、延出部３７ａ、３７ｂと、凹部２７ａ、２７ｂのそれぞれは、従動プーリ２３を基準として面対称に形成されている。よって、各構成については、従動プーリ２３を基準として第１軸受３０ａ側に配置された構成を挙げて説明し、第２軸受３０ｂ側に配置された構成の説明を省略する。また、以下の実施形態においても、従動プーリ２３を境界として、第１軸受３０ａ側と第２軸受３０ｂ側に分かれて配置され、かつ、従動プーリ２３を基準として対称に形成される構成については、第１軸受３０ａ側に配置された構成を挙げて説明する。 The preload applying members 41a and 41b, the first seal members 60a and 60b, the extending portions 37a and 37b, and the recesses 27a and 27b are respectively bounded by the driven pulley 23 on the first bearing 30a side and the second. The bearings are arranged separately on the 30b side. The preload applying members 41a and 41b, the first seal members 60a and 60b, the extending portions 37a and 37b, and the recesses 27a and 27b are each formed plane-symmetrically with respect to the driven pulley 23. Therefore, each configuration will be described with reference to the configuration arranged on the first bearing 30a side with the driven pulley 23 as a reference, and the description of the configuration arranged on the second bearing 30b side will be omitted. Further, also in the following embodiments, the configuration in which the driven pulley 23 is defined as a boundary and is separately arranged on the first bearing 30a side and the second bearing 30b side and is formed symmetrically with respect to the driven pulley 23 is defined. The configuration arranged on the first bearing 30a side will be described.

予圧付与部材４１ａは、ゴム製の予圧用弾性体４２と、第１芯金４３と、第２芯金４４と、を備える。第１芯金４３と第２芯金４４は、予圧用弾性体４２の形状を保持するためのものであり、加硫接着により予圧用弾性体４２と一体になっている。 The preload applying member 41a includes a rubber preload elastic body 42, a first core metal 43, and a second core metal 44. The first core metal 43 and the second core metal 44 are for maintaining the shape of the preload elastic body 42, and are integrated with the preload elastic body 42 by vulcanization adhesion.

第１シール部材６０ａは、ナット１３の外周面１３ａに摺接するゴム製の内周シール用弾性体６０ｃと、外輪３１ａの内周面に嵌合するとともに内周シール用弾性体６０ｃを支持する第３芯金６０ｄと、を備える。これにより、外輪３１ａの内周側であって第１方向側が閉塞される。 The first sealing member 60a is a rubber inner peripheral sealing elastic body 60c that is in sliding contact with the outer peripheral surface 13a of the nut 13, and is fitted to the inner peripheral surface of the outer ring 31a and supports the inner peripheral sealing elastic body 60c. It is provided with a 3-core metal 60d. As a result, the inner peripheral side of the outer ring 31a and the first direction side are closed.

また、第１芯金４３と第３芯金６０ｄとが連続し、第１シール部材６０ａと予圧付与部材４１ａとが一体化している。これにより、第１シール部材６０ａの第３芯金６０ｄを外輪３１ａ内に嵌め込むと、予圧付与部材４１ａも併せて組み付けられるため、組み付け作業の工数が削減する。 Further, the first core metal 43 and the third core metal 60d are continuous, and the first seal member 60a and the preload applying member 41a are integrated. As a result, when the third core metal 60d of the first seal member 60a is fitted into the outer ring 31a, the preload applying member 41a is also assembled, so that the man-hours for the assembling work are reduced.

凹部２７ａは、従動プーリ２３の第１側面２３ｄにおいて、外輪３１ａと対向する部位を窪ませて成る。凹部２７ａ内には、延出部３７ａの端部３７ｃが入り込んでいる。また、延出部３７ａの端部３７ｃと凹部２７ａとは、接触していない。延出部３７ａの端部３７と凹部２７ａとの間には、微小な隙間が形成されて、断面略Ｃ字状のラビリンスシールを構成している。さらに凹部２７ａ内には図示しないグリスが充填されている。 The recess 27a is formed by recessing a portion of the first side surface 23d of the driven pulley 23 that faces the outer ring 31a. The end portion 37c of the extending portion 37a is inserted into the recess 27a. Further, the end portion 37c of the extending portion 37a and the recessed portion 27a are not in contact with each other. A minute gap is formed between the end portion 37 of the extending portion 37a and the recessed portion 27a to form a labyrinth seal having a substantially C-shaped cross section. Further, the recess 27a is filled with grease (not shown).

以上で説明したように、動力伝達装置１Ｆにおいて、従動プーリ２３において外輪３１ａ、３１ｂの端面と対向する側面には、凹部２７ａ、２７ｂが形成され、外輪３１ａ、３１ｂには、凹部２７ａ、２７ｂ内に向かって延出する延出部３７ａ、３７ｂが形成され、延出部３７ａ、３７ｂの端部３７ｃ、３７ｄは、凹部２７ａ、２７ｂ内に入り込み、延出部３７ａ、３７ｂの端部３７ｃ、３７ｄと凹部２７ａ、２７ｂとの間は、微小隙間によるラビリンス構造となっている。これにより、外輪３１ａ、３１ｂと従動プーリ２３との間が閉塞され、従動プーリ２３とベルト２５との摩耗粉が第１軸受３０ａ及び第２軸受３０ｂ内に侵入し難くなる。 As described above, in the power transmission device 1F, recesses 27a and 27b are formed on the side surfaces of the driven pulley 23 facing the end faces of the outer rings 31a and 31b, and the outer rings 31a and 31b are inside the recesses 27a and 27b. The extending portions 37a and 37b are formed, and the ends 37c and 37d of the extending portions 37a and 37b enter into the recesses 27a and 27b, and the ends 37c and 37d of the extending portions 37a and 37b are formed. A labyrinth structure with a minute gap is formed between the recesses 27a and 27b. As a result, the outer rings 31a and 31b and the driven pulley 23 are closed, and wear debris from the driven pulley 23 and the belt 25 is less likely to enter the first bearing 30a and the second bearing 30b.

また、動力伝達装置１Ｆの凹部２７ａ、２７ｂ内には、図示しないグリスが充填されている。これにより摩耗粉がグリスに吸着されるため、摩耗粉が第１軸受３０ａ及び第２軸受３０ｂ内にさらに侵入し難くなる。 Further, the recesses 27a and 27b of the power transmission device 1F are filled with grease (not shown). As a result, the wear debris is adsorbed on the grease, so that the wear debris is less likely to enter the first bearing 30a and the second bearing 30b.

また、動力伝達装置１Ｆにおいて、外輪３１ａ、３１ｂの両端部のうち予圧付与部材４１ａ、４１ｂ側を向く端部には、ナット１３の外周面１３ａに摺接する第１シール部材６０ａ、６０ｂが設けられている。これにより、予圧付与部材４１ａ、４１ｂ側にある異物が第１軸受３０ａ及び第２軸受３０ｂ内に侵入し難くなる。 Further, in the power transmission device 1F, first seal members 60a and 60b that are in sliding contact with the outer peripheral surface 13a of the nut 13 are provided at the ends of the outer rings 31a and 31b facing the preload applying members 41a and 41b. ing. As a result, foreign matter on the preload applying members 41a and 41b is less likely to enter the first bearing 30a and the second bearing 30b.

（実施形態５）
図１３は、実施形態５の動力伝達装置の断面図である。実施形態５の動力伝達装置１Ｇは、外輪３１ａ、３１ｂには、延出部３７ａ、３７ｂに代えて従動プーリ２３側に向かって延出するシールド部材３８ａ、３８ｂが設けられている点が第４実施形態の動力伝達装置１Ｆと相違する。 (Embodiment 5)
FIG. 13 is a cross-sectional view of the power transmission device of the fifth embodiment. The fourth point of the power transmission device 1G of the fifth embodiment is that the outer rings 31a and 31b are provided with shield members 38a and 38b extending toward the driven pulley 23 side instead of the extending portions 37a and 37b. It is different from the power transmission device 1F of the embodiment.

シールド部材３８ａは、金属製の環状部材であり、外輪３１ａの内周側に嵌合している。よって、シールド部材３８ａは、外輪３１ａに対し取り外し可能となっている。シールド部材３８ａは、外輪３１ａの端部から従動プーリ２３に向かって延出する円筒状の円筒部３８ｃを有している。円筒部３８ｃの端部は、従動プーリ２３の側面に形成された凹部２８ａ内に入り込んでいる。円筒部３８ｃの端部と凹部２８ａとは接触していない。円筒部３８ｃの端部と凹部２８ａとの間には、微小な隙間が形成されて、断面略Ｃ字状のラビリンスシールを構成している。さらに凹部２８ａ内には図示しないグリスが塗られている。 The shield member 38a is an annular member made of metal and is fitted to the inner peripheral side of the outer ring 31a. Therefore, the shield member 38a is removable with respect to the outer ring 31a. The shield member 38a has a cylindrical cylindrical portion 38c extending from the end of the outer ring 31a toward the driven pulley 23. The end of the cylindrical portion 38c penetrates into the recess 28a formed on the side surface of the driven pulley 23. The end of the cylindrical portion 38c is not in contact with the recess 28a. A minute gap is formed between the end of the cylindrical portion 38c and the recess 28a to form a labyrinth seal having a substantially C-shaped cross section. Further, grease (not shown) is applied to the inside of the recess 28a.

以上で説明したように、動力伝達装置１Ｇは、外輪３１ａ、３１ｂに固定されるとともに、従動プーリ２３の側面に向かって延出し、外輪３１ａ、３１ｂと従動プーリ２３との隙間Ｓ１、Ｓ２を閉塞するシールド部材３８ａ、３８ｂを備え、従動プーリ２３において外輪３１ａ、３１ｂの端面と対向する側面には、凹部２８ａ、２８ｂが形成され、シールド部材３８の円筒部３８ｃ、３８ｄの端部は、凹部２８ａ、２８ｂ内に入り込んでいる。シールド部材３８ａ、３８ｂの円筒部３８ｃ、３８ｄの端部と凹部２８ａ、２８ｂとの間は、微小隙間によるラビリンス構造となっている。これにより、外輪３１ａ、３１ｂと従動プーリ２３との間が閉塞され、従動プーリ２３とベルト２５との摩耗粉が第１軸受３０ａ及び第２軸受３０ｂ内に侵入し難くなる。さらに凹部２８ａ、２８ｂ内には、グリスが塗られているため、摩耗粉が第１軸受３０ａ及び第２軸受３０ｂ内にさらに侵入し難い。 As described above, the power transmission device 1G is fixed to the outer rings 31a and 31b and extends toward the side surface of the driven pulley 23 to close the gaps S1 and S2 between the outer rings 31a and 31b and the driven pulley 23. Shield members 38a and 38b are provided, recesses 28a and 28b are formed on the side surfaces of the driven pulley 23 facing the end faces of the outer rings 31a and 31b, and the ends of the cylindrical portions 38c and 38d of the shield member 38 are recesses 28a. , 28b. A labyrinth structure with a minute gap is formed between the ends of the cylindrical portions 38c and 38d of the shield members 38a and 38b and the recesses 28a and 28b. As a result, the outer rings 31a and 31b and the driven pulley 23 are closed, and wear debris from the driven pulley 23 and the belt 25 is less likely to enter the first bearing 30a and the second bearing 30b. Further, since the recesses 28a and 28b are coated with grease, it is more difficult for wear debris to enter the first bearing 30a and the second bearing 30b.

なお、外輪３１ａ、３１ｂには中心軸ＡＸ方向の寸法誤差があるため、この寸法誤差によりシールド部材３８ａ、３８ｂの円筒部３８ｃ、３８ｄの端部が凹部２８ａ、２８ｂの内面と接触して第１軸受３０ａ及び第２軸受３０ｂの予圧量が変化してしまう可能性がある。又は、円筒部３８ｃ、３８ｄの端部が凹部２８ａ、２８ｂ内に入り込まずに、ラビリンス構造を形成できない可能がある。しかしながら、シールド部材３８ａ、３８ｂは、外輪３１ａ、３１ｂに対し取り外し可能となっている。よって、円筒部３８ｃ、３８ｄの長さの異なるシールド部材３８ａ、３８ｂを複数用意し、実施品ごとに適切なシールド部材３８ａ、３８ｂを選んで取り付けることができる。以上から、本実施形態によれば、円筒部３８ｃ、３８ｄの端部と凹部２８ａ、２８ｂの内面との間に形成される微小隙間（隙間Ｓ１、Ｓ２）を適切に管理することができる。よって、円筒部３８ｃ、３８ｄの端部が凹部２８ａ、２８ｂの内面と接触して第１軸受３０ａ及び第２軸受３０ｂの予圧量が変化する、ということを回避できる。または、円筒部３８ｃ、３８ｄの端部が凹部２８ａ、２８ｂ内に入り込まずラビリンス構造を形成できない、ということを回避できる。 Since the outer rings 31a and 31b have a dimensional error in the central axis AX direction, the ends of the cylindrical portions 38c and 38d of the shield members 38a and 38b come into contact with the inner surfaces of the recesses 28a and 28b due to this dimensional error. The preload amount of the bearing 30a and the second bearing 30b may change. Alternatively, the labyrinth structure may not be formed without the ends of the cylindrical portions 38c and 38d entering the recesses 28a and 28b. However, the shield members 38a and 38b are removable with respect to the outer rings 31a and 31b. Therefore, a plurality of shield members 38a and 38b having different lengths of the cylindrical portions 38c and 38d can be prepared, and appropriate shield members 38a and 38b can be selected and attached to each of the implemented products. From the above, according to the present embodiment, it is possible to appropriately manage the minute gaps (gap S1, S2) formed between the ends of the cylindrical portions 38c and 38d and the inner surfaces of the recesses 28a and 28b. Therefore, it is possible to avoid that the end portions of the cylindrical portions 38c and 38d come into contact with the inner surfaces of the recesses 28a and 28b and the preload amount of the first bearing 30a and the second bearing 30b changes. Alternatively, it can be avoided that the ends of the cylindrical portions 38c and 38d do not enter the recesses 28a and 28b and the labyrinth structure cannot be formed.

（実施形態６）
図１４は、実施形態６の動力伝達装置の断面図である。実施形態６の動力伝達装置１Ｈは、さらに第２シール部材６１ａ、６１ｂを備える点で、第４実施形態の動力伝達装置１Ｆと相違する。第２シール部材６１ａ、６１ｂは、外輪３１ａ、３１ｂの延出部３７ａ、３７ｂの内周側に嵌合する第４芯金６１ｃ、６１ｄと、第４芯金６１ｃ、６１ｄに支持されてナット１３の外周面１３ａに摺接する内周シール用弾性体６１ｅ、６１ｆと、を備える。 (Embodiment 6)
FIG. 14 is a cross-sectional view of the power transmission device of the sixth embodiment. The power transmission device 1H of the sixth embodiment is different from the power transmission device 1F of the fourth embodiment in that the second seal members 61a and 61b are further provided. The second seal members 61a and 61b are supported by the fourth core metal 61c and 61d and the fourth core metal 61c and 61d that are fitted to the inner peripheral side of the extending portions 37a and 37b of the outer rings 31a and 31b, and the nut 13 The elastic bodies 61e and 61f for inner peripheral sealing that are in sliding contact with the outer peripheral surface 13a of the above are provided.

以上で説明したように、動力伝達装置１Ｈは、外輪３１ａ、３１ｂの従動プーリ２３側を向く端部には、ナット１３の外周面１３ａに摺接する第２シール部材６１ａ、６１ｂが設けられている。これにより、従動プーリ２３とベルト２５との摩耗粉が第１軸受３０ａ及び第２軸受３０ｂ内にさらに侵入し難くなる。 As described above, the power transmission device 1H is provided with second seal members 61a and 61b that are in sliding contact with the outer peripheral surface 13a of the nut 13 at the ends of the outer rings 31a and 31b facing the driven pulley 23 side. .. As a result, wear debris from the driven pulley 23 and the belt 25 is less likely to enter the first bearing 30a and the second bearing 30b.

（実施形態７）
図１５は、実施形態７の動力伝達装置の断面図である。実施形態７の動力伝達装置１Ｉは、シールド部材３８ａ、３８ｂに代えて、凹部２８ａ、２８ｂ内に入り込む円筒部３９ｃ、３９ｄを有するシールド部材３９ａ、３９ｂを備える点において、実施形態５の動力伝達装置１Ｇと相違する。また、シールド部材３９ａ、３９ｂにはシール用弾性体３９ｅ、３９ｆが設けられている。さらに、シール用弾性体３９ｅ、３９ｆが摺接する部位には、断面形状がＬ字状の被覆部品６２ａ、６２ｂが設けられている点で実施形態５の動力伝達装置１Ｇと相違する。 (Embodiment 7)
FIG. 15 is a cross-sectional view of the power transmission device of the seventh embodiment. The power transmission device 1I of the seventh embodiment includes the shield members 39a and 39b having cylindrical portions 39c and 39d that enter into the recesses 28a and 28b instead of the shield members 38a and 38b. Different from 1G. Further, the shield members 39a and 39b are provided with elastic bodies 39e and 39f for sealing. Further, it differs from the power transmission device 1G of the fifth embodiment in that the covering parts 62a and 62b having an L-shaped cross section are provided at the portions where the sealing elastic bodies 39e and 39f are in sliding contact with each other.

シールド部材３９ａは、芯金であり、従動プーリ２３に向かって延出して凹部２８ａ内に入り込む円筒部３９ｃを有している。円筒部３９ｃの端部と凹部２８ａとの間には、微小な隙間が形成されて、断面略Ｃ字状のラビリンスシールを構成している。凹部２８ａ内には図示しないグリスが塗られている。また、シールド部材３９ａは、外輪３１ａの内周側に嵌合している。よって、シールド部材３９ａは、外輪３１ａに対し取り外し可能となっている。よって、円筒部３９ｃ、３９ｄの長さの異なるシールド部材３９ａ、３９ｂを複数用意し、実施品ごとに適切なシールド部材３９ａ、３９ｂを選んで取り付けることができる。 The shield member 39a is a core metal and has a cylindrical portion 39c that extends toward the driven pulley 23 and enters the recess 28a. A minute gap is formed between the end of the cylindrical portion 39c and the recess 28a to form a labyrinth seal having a substantially C-shaped cross section. Grease (not shown) is applied to the inside of the recess 28a. Further, the shield member 39a is fitted to the inner peripheral side of the outer ring 31a. Therefore, the shield member 39a is removable with respect to the outer ring 31a. Therefore, a plurality of shield members 39a and 39b having different lengths of the cylindrical portions 39c and 39d can be prepared, and appropriate shield members 39a and 39b can be selected and attached to each of the implemented products.

シール用弾性体３９ｅは、加硫接着によってシールド部材３９ａに固定されている。被覆部品６２ａは、金属製の部品であり、ナット１３の外周面１３ａや従動プーリ２３の第１側面２３ｄを覆っている。これにより、シール用弾性体３９ｅが、表面粗さが大きいナット１３の外周面１３ａ等に摺接して大きく摩耗する、ということが回避される。 The sealing elastic body 39e is fixed to the shield member 39a by vulcanization adhesion. The covering part 62a is a metal part and covers the outer peripheral surface 13a of the nut 13 and the first side surface 23d of the driven pulley 23. As a result, it is possible to prevent the sealing elastic body 39e from being in sliding contact with the outer peripheral surface 13a or the like of the nut 13 having a large surface roughness and being greatly worn.

（実施形態８）
図１６は、実施形態８の動力伝達装置の断面図である。実施形態８の動力伝達装置１Ｊは、予圧付与部材４０ａ、４０ｂに代えて予圧付与部材４５を用いている点において、実施形態１の動力伝達装置１と相違する。また、実施形態８では、一つの予圧付与部材４５により、第１軸受３０ａ及び第２軸受３０ｂに予圧を与えている。 (Embodiment 8)
FIG. 16 is a cross-sectional view of the power transmission device of the eighth embodiment. The power transmission device 1J of the eighth embodiment is different from the power transmission device 1 of the first embodiment in that the preload applying member 45 is used instead of the preload applying members 40a and 40b. Further, in the eighth embodiment, the preload is applied to the first bearing 30a and the second bearing 30b by one preload applying member 45.

予圧付与部材４５は、中心軸ＡＸ方向における寸法Ｃが調整された間座である。よって、実施形態８においては、定位置予圧により、第１軸受３０ａ及び第２軸受３０ｂに予圧を付与している。予圧付与部材４５の材料は、鉄、アルミニウム合金、マグネシウム合金、或いは、樹脂が挙げられる。また、予圧付与部材４５における中心軸ＡＸ方向の寸法Ｃは、次のような式１となっている。 The preload applying member 45 is a spacer whose dimension C in the direction of the central axis AX is adjusted. Therefore, in the eighth embodiment, the preload is applied to the first bearing 30a and the second bearing 30b by the fixed position preload. Examples of the material of the preload applying member 45 include iron, aluminum alloy, magnesium alloy, and resin. Further, the dimension C of the preload applying member 45 in the central axis AX direction is given by the following equation 1.


Ｃ＝δ＋Ｂ−（Ａ−Δ） ・・・（式１）
C = δ + B- (A-Δ) ... (Equation 1)

式１において、Ａは、第１軸受３０ａと第２軸受３０ｂとにおいて予圧が付与されていない状態の中心軸ＡＸ方向の寸法である。（Ａ−Δ）は、第１軸受３０ａと第２軸受３０ｂとにおいて予圧が付与された状態の中心軸ＡＸ方向の寸法である。Ｂは、第１本体部１０の段差面１０１ａと第２本体１０３の段差面１０３ａとの間の距離である。σは、予圧付与部材４５が予圧を付与していない状態から予圧を付与した状態に生じた弾性変形量である。 In the formula 1, A is a dimension in the direction of the central axis AX in a state where no preload is applied to the first bearing 30a and the second bearing 30b. (A−Δ) is a dimension in the direction of the central axis AX in a state where a preload is applied to the first bearing 30a and the second bearing 30b. B is the distance between the stepped surface 101a of the first main body 10 and the stepped surface 103a of the second main body 103. σ is the amount of elastic deformation generated from the state in which the preload applying member 45 is not applied to the preload to the state in which the preload is applied.

上記した動力伝達装置１Ｊによれば、間座である予圧付与部材４５の材料を適宜選択することで、温度変化に伴う予圧量の変化を緩和することができる。詳細に説明すると、温度上昇により膨張すると、ハウジング１００と外輪３１ａ、３１ｂは、中心軸ＡＸ方向の寸法が大きくなる。仮に、ハウジング１００がアルミニウム合金製であり、外輪３１ａ、３１ｂが軸受鋼製の場合、鉄製の予圧付与部材４５が選択されると、アルミニウム合金は鉄よりも線膨張係数の大きいため、予圧付与部材４５の膨張量がハウジング１００の膨張量よりも小さく、定位置予圧による予圧量が低下してしまう。よって、アルミニウム合金製のハウジング１００と同じ材料で形成されたアルミニウム合金製の予圧付与部材４５を選択することで、温度変化に伴う予圧量の低下が緩和される。また、これによれば、樹脂で形成された予圧付与部材４５を選択する場合よりも予圧量の変化を緩和することができる。また、上記した動力伝達装置１Ｊによれば、１つの予圧付与部材４５により、第１軸受３０ａ及び第２軸受３０ｂに定圧予圧を付与しており、動力伝達装置１Ｊの中心軸ＡＸ方向の寸法を小さくして、装置の小型化を実現している。 According to the power transmission device 1J described above, the change in the preload amount due to the temperature change can be alleviated by appropriately selecting the material of the preload applying member 45 which is the spacer. More specifically, when the housing 100 and the outer rings 31a and 31b expand due to an increase in temperature, the dimensions of the housing 100 and the outer rings 31a and 31b become larger in the central axis AX direction. If the housing 100 is made of an aluminum alloy and the outer rings 31a and 31b are made of bearing steel, if the iron preload applying member 45 is selected, the aluminum alloy has a larger coefficient of linear expansion than iron, so that the preload applying member The amount of expansion of 45 is smaller than the amount of expansion of the housing 100, and the amount of preload due to the fixed position preload decreases. Therefore, by selecting the aluminum alloy preload applying member 45 made of the same material as the aluminum alloy housing 100, the decrease in the preload amount due to the temperature change is alleviated. Further, according to this, the change in the preload amount can be relaxed as compared with the case where the preload applying member 45 made of resin is selected. Further, according to the power transmission device 1J described above, a constant pressure preload is applied to the first bearing 30a and the second bearing 30b by one preload applying member 45, and the dimension of the power transmission device 1J in the central axis AX direction is determined. It is made smaller to realize the miniaturization of the device.

（実施形態９）
図１７は、実施形態９の動力伝達装置の断面図である。図１８は、予圧付与部材と高負荷吸収部とのみを抽出し、中心軸ＡＸ方向から視た模式図である。図１７に示すように、実施形態８の動力伝達装置１Ｋは、予圧付与部材４０ａ、４０ｂに代えて、一対の環状部材６５ａ、６５ｂを備える点で、実施形態１の動力伝達装置１と相違する。 (Embodiment 9)
FIG. 17 is a cross-sectional view of the power transmission device of the ninth embodiment. FIG. 18 is a schematic view in which only the preload applying member and the high load absorbing portion are extracted and viewed from the central axis AX direction. As shown in FIG. 17, the power transmission device 1K of the eighth embodiment is different from the power transmission device 1 of the first embodiment in that it includes a pair of annular members 65a and 65b instead of the preload applying members 40a and 40b. ..

環状部材６５ａは、芯金６６と、芯金６６に加硫接着されたゴム６７と、を備える。芯金６６は、外輪３１ａの外周面に嵌合する外周嵌合部６６ａと、外輪３１ａにおける第１方向側の端面に当接する当接部６６ｂと、当接部６６ｂから径方向内側に延出する延出部６６ｃと、を備える。外周嵌合部６６ａは、外輪３１ａの外周面に形成された凹部３９内に配置されている。これにより、外周嵌合部６６ａは、外輪３１ａの外周面よりも径方向内側に位置している。 The annular member 65a includes a core metal 66 and a rubber 67 vulcanized and bonded to the core metal 66. The core metal 66 extends inward in the radial direction from the outer peripheral fitting portion 66a that fits on the outer peripheral surface of the outer ring 31a, the abutting portion 66b that abuts on the end surface of the outer ring 31a on the first direction side, and the abutting portion 66b. An extension portion 66c is provided. The outer peripheral fitting portion 66a is arranged in the recess 39 formed on the outer peripheral surface of the outer ring 31a. As a result, the outer peripheral fitting portion 66a is located radially inside the outer peripheral surface of the outer ring 31a.

ゴム６７は、外周嵌合部６６ａの外周側に形成された外周シール用弾性体６７ａと、当接部６６ｂの第１方向側の側面に形成された高負荷吸収部６７ｂと、高負荷吸収部６７ｂから第１方向側に突出する予圧付与部材６７ｃと、延出部６６ｃに沿って径方向内側に延出する内周シール用弾性体６７ｄと、を備える。また、外周シール用弾性体６７ａと高負荷吸収部６７ｂと予圧付与部材６７ｃと内周シール用弾性体６７ｄとは連続しており、一体的に形成されている。 The rubber 67 includes an outer peripheral sealing elastic body 67a formed on the outer peripheral side of the outer peripheral fitting portion 66a, a high load absorbing portion 67b formed on the side surface of the contact portion 66b on the first direction side, and a high load absorbing portion. A preload applying member 67c projecting from the 67b to the first direction side, and an elastic body 67d for inner circumference sealing extending inward in the radial direction along the extending portion 66c are provided. Further, the outer peripheral sealing elastic body 67a, the high load absorbing portion 67b, the preload applying member 67c, and the inner peripheral sealing elastic body 67d are continuous and integrally formed.

外周シール用弾性体６７ａは、第２本体１０３の内周面１０３ｂに摺接している。これにより、第２本体１０３と外輪３１ａとの間からグリスが漏出し難くなる。また、外周シール用弾性体６７ａによって、外輪３１ａの径方向の振動が吸収され、いわゆるラトル音の発生が抑制される。内周シール用弾性体６７ｄは、ナット１３の外周面１３ａに摺接している。よって、第１方向側から第１軸受３０ａ内に異物が侵入することが抑制される。 The outer peripheral sealing elastic body 67a is in sliding contact with the inner peripheral surface 103b of the second main body 103. As a result, grease is less likely to leak from between the second main body 103 and the outer ring 31a. Further, the elastic body 67a for the outer peripheral seal absorbs the vibration in the radial direction of the outer ring 31a, and suppresses the generation of so-called rattle noise. The elastic body 67d for inner peripheral sealing is in sliding contact with the outer peripheral surface 13a of the nut 13. Therefore, it is possible to prevent foreign matter from entering the first bearing 30a from the first direction side.

高負荷吸収部６７ｂと予圧付与部材６７ｃは、組み付け前において中心軸ＡＸ方向の厚みは同じに形成されている。高負荷吸収部６７ｂにおける径方向の長さはＬ１である。予圧付与部材６７ｃにおける径方向の長さはＬ２である。よって、径方向の長さに関し、高負荷吸収部６７ｂの方が予圧付与部材６７ｃよりも長く形成されている。つまり、中心軸ＡＸに沿って切った場合の断面積は、予圧付与部材６７ｃよりも高負荷吸収部６７ｂの方が大きい。 The high load absorbing portion 67b and the preload applying member 67c are formed to have the same thickness in the central axis AX direction before assembly. The radial length of the high load absorbing portion 67b is L1. The radial length of the preload applying member 67c is L2. Therefore, with respect to the radial length, the high load absorbing portion 67b is formed longer than the preload applying member 67c. That is, the cross-sectional area when cut along the central axis AX is larger in the high load absorbing portion 67b than in the preload applying member 67c.

高負荷吸収部６７ｂと予圧付与部材６７ｃは、第２本体１０３の段差面１０３ａと外輪３１ａとの間に組み付けられ、中心軸ＡＸ方向に圧縮荷重が作用している。これにより、断面積が小さい予圧付与部材６７ｃの方が高負荷吸収部６７ｂよりも大きく変形している。そして、予圧付与部材６７ｃは、外輪３１ａを押圧し、第１軸受３０ａに予圧を付与している。一方で、ラック８８ｂに中心軸ＡＸに大きな荷重が作用した場合、高負荷吸収部６７ｂが変形して負荷を吸収する。また、図１８に示すように、高負荷吸収部６７ｂは、中心軸ＡＸを中心として環状に形成されている。予圧付与部材６７ｃは、中心軸ＡＸ方向から視て矩形状に形成された複数の突部６７ｅにより構成される。 The high load absorbing portion 67b and the preload applying member 67c are assembled between the stepped surface 103a of the second main body 103 and the outer ring 31a, and a compressive load acts in the direction of the central axis AX. As a result, the preload applying member 67c having a small cross-sectional area is deformed more than the high load absorbing portion 67b. Then, the preload applying member 67c presses the outer ring 31a to apply the preload to the first bearing 30a. On the other hand, when a large load acts on the central axis AX on the rack 88b, the high load absorbing portion 67b is deformed to absorb the load. Further, as shown in FIG. 18, the high load absorbing portion 67b is formed in an annular shape about the central axis AX. The preload applying member 67c is composed of a plurality of protrusions 67e formed in a rectangular shape when viewed from the central axis AX direction.

以上で説明したように、動力伝達装置１Ｋは、第１軸受３０ａ及び第２軸受３０ｂのいずれか一方の外輪３１ａ、３１ｂに固定される芯金６６と、芯金６６に支持されて外輪３１ａ、３１ｂの内周側を閉塞する内周シール用弾性体６７ｄと、を有し、芯金６６は、外輪３１ａ、３１ｂの外周面に嵌合する筒状の外周嵌合部６６ａを有し、外輪３１ａ、３１ｂの外周面には、径方向内側に窪み、外周嵌合部６６ａを収容する凹部３９が形成されている。これにより、外周嵌合部６６ａがハウジング１００に当接して外輪３１ａの摺動を阻害する、ということを防止することができる。 As described above, the power transmission device 1K includes a core metal 66 fixed to the outer rings 31a and 31b of either the first bearing 30a and the second bearing 30b, and an outer ring 31a supported by the core metal 66. The core metal 66 has a tubular outer peripheral fitting portion 66a that fits on the outer peripheral surfaces of the outer rings 31a and 31b, and has an elastic body 67d for inner circumference sealing that closes the inner peripheral side of 31b. The outer peripheral surfaces of 31a and 31b are formed with recesses 39 that are recessed inward in the radial direction and accommodate the outer peripheral fitting portion 66a. As a result, it is possible to prevent the outer peripheral fitting portion 66a from coming into contact with the housing 100 and hindering the sliding of the outer ring 31a.

動力伝達装置１Ｋは、外輪３１ａ、３１ｂの外周面とハウジング１００の内周面１０１ｂ、１０３ｂとの間を閉塞する外周シール用弾性体６７ａを備え、外周シール用弾性体６７ａは、外周嵌合部６６ａの外周面に固定されてハウジング１００の内周面１０１ｂ、１０３ｂに摺接する。外周シール用弾性体６７ａによれば、外輪３１ａ、３１ｂとハウジング１００との間からグリスが漏出することが抑制され、外輪３１ａ、３１ｂの摺動性を確保できる。また、外周シール用弾性体６７ａによって外輪３１ａ、３１ｂの径方向の振動が吸収され、いわゆるラトル音の発生が抑制される。さらに、芯金６６を外輪３１ａ、３１ｂに組み付けると、外周シール用弾性体６７ａも併せて組み付けられるため、組み付け作業の工数が削減する。 The power transmission device 1K includes an outer peripheral sealing elastic body 67a that closes between the outer peripheral surfaces of the outer rings 31a and 31b and the inner peripheral surfaces 101b and 103b of the housing 100, and the outer peripheral sealing elastic body 67a is an outer peripheral fitting portion. It is fixed to the outer peripheral surface of 66a and is in sliding contact with the inner peripheral surfaces 101b and 103b of the housing 100. According to the elastic body 67a for the outer peripheral seal, the leakage of grease from between the outer rings 31a and 31b and the housing 100 is suppressed, and the slidability of the outer rings 31a and 31b can be ensured. Further, the elastic body 67a for the outer peripheral seal absorbs the radial vibrations of the outer rings 31a and 31b, and the generation of so-called rattle noise is suppressed. Further, when the core metal 66 is assembled to the outer rings 31a and 31b, the elastic body 67a for the outer peripheral seal is also assembled, so that the man-hours for the assembling work are reduced.

動力伝達装置１Ｋは、予圧付与部材６７ｃと外輪３１ａ、３１ｂとの間に介在して、中心軸ＡＸ方向の高負荷を吸収するゴム製の高負荷吸収部６７ｂを備える。予圧付与部材６７ｃは、ゴム製であり、中心軸ＡＸ方向で切った断面積が高負荷吸収部６７Ｂよりも小さい。予圧付与部材６７ｃと高負荷吸収部６７ｂは、芯金６６に支持されている。これにより、高負荷吸収部６７ｂ及び予圧付与部材６７ｃを組み付けた場合、予圧付与部材６７ｃが変形して外輪３１ａを押圧し、第１軸受３０ａ及び第２軸受３０ｂに予圧を与える。一方で、中心軸ＡＸ方向に高負荷が作用した場合、高負荷吸収部６７ｂが高負荷を吸収する。よって、予圧付与部材６７ｃに高負荷が作用して破断する、ということが回避される。また、芯金６６を外輪３１ａ、３１ｂに組み付けると、予圧付与部材６７ｃと高負荷吸収部６７ｂも組み付けられるため、組み付け作業の工数が低減する。 The power transmission device 1K includes a rubber high load absorbing portion 67b that is interposed between the preload applying member 67c and the outer rings 31a and 31b to absorb a high load in the direction of the central axis AX. The preload applying member 67c is made of rubber, and the cross-sectional area cut in the central axis AX direction is smaller than that of the high load absorbing portion 67B. The preload applying member 67c and the high load absorbing portion 67b are supported by the core metal 66. As a result, when the high load absorbing portion 67b and the preload applying member 67c are assembled, the preload applying member 67c is deformed to press the outer ring 31a and preload the first bearing 30a and the second bearing 30b. On the other hand, when a high load acts in the direction of the central axis AX, the high load absorbing unit 67b absorbs the high load. Therefore, it is avoided that a high load acts on the preload applying member 67c to break the member. Further, when the core metal 66 is assembled to the outer rings 31a and 31b, the preload applying member 67c and the high load absorbing portion 67b are also assembled, so that the man-hours for the assembling work are reduced.

動力伝達装置１Ｋの予圧付与部材６７ｃは、周方向に互いに離隔して配置される複数の突部６７ｅを備える。これにより、突部６７ｅの数を変更することで、予圧付与部材６７ｃの予圧量を調整することができる。尚、外周シール用弾性体６７ａと高負荷吸収部６７ｂと予圧付与部材６７ｃと内周シール用弾性体６７ｄとは、ゴム６７により連続して一体化されているが、他の弾性体により形成したり、複数の材料を組み合わせて形成したりすることもできる。例えば、予圧付与部材６７ｃを、樹脂、混合材料、等の材料により形成してもよいし、皿ばね等の弾性部材により構成してもよい。また、上記する混合材料としては、ゴムと樹脂とを混合させた材料があり、ゴムと樹脂の混合比を調整することで、材料の硬さを変えることができる。さらには、高負荷吸収部６７ｂは、予圧付与部材６７ｃとは異なる材料で形成することもできる。 The preload applying member 67c of the power transmission device 1K includes a plurality of protrusions 67e arranged apart from each other in the circumferential direction. Thereby, the preload amount of the preload applying member 67c can be adjusted by changing the number of the protrusions 67e. The outer peripheral sealing elastic body 67a, the high load absorbing portion 67b, the preload applying member 67c, and the inner peripheral sealing elastic body 67d are continuously integrated by the rubber 67, but are formed by other elastic bodies. Alternatively, it can be formed by combining a plurality of materials. For example, the preload applying member 67c may be formed of a material such as a resin or a mixed material, or may be formed of an elastic member such as a disc spring. Further, as the above-mentioned mixed material, there is a material in which rubber and resin are mixed, and the hardness of the material can be changed by adjusting the mixing ratio of rubber and resin. Further, the high load absorbing portion 67b can be formed of a material different from that of the preload applying member 67c.

１、１Ａ、１Ｂ、１Ｃ、１Ｄ、１Ｅ、１Ｆ、１Ｇ、１Ｈ、１Ｉ、１Ｊ、１Ｋ 動力伝達装置
１０、１０Ａ ボールねじ装置
１１ ねじ軸
１３ ナット
１５ ボール
１７ 位置決め部材
２０ プーリ装置
２１ 駆動プーリ
２３ 従動プーリ
２５ ベルト
３０ａ 第１軸受
３０ｂ 第２軸受
３１ａ、３１ｂ 外輪
３３ａ、３３ｂ 内輪
３５ａ、３５ｂ 転動体
３６ａ、３６ｂ グリス用溝
４０ａ、４０ｂ、４１ａ、４１ｂ、４５、６７ｃ 予圧付与部材
６５ａ、６５ｂ 環状部材
６６ 芯金
６７ａ 外周シール用弾性体
６７ｂ 高負荷吸収部
６７ｄ 内周シール用弾性体
８０ 電動パワーステアリング装置
１００ ハウジング
１０１ 第１本体
１０３ 第２本体
１０５ 第３本体
ＡＸ 中心軸
ＣＮ 仮想線
ＣＮａ、ＣＮｂ 基準線
ＬＣ１、ＬＣ２、ＬＣ３、ＬＣ４ 接触角の延長線 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K Power transmission device 10, 10A Ball screw device 11 Screw shaft 13 Nut 15 Ball 17 Positioning member 20 Pulley device 21 Drive pulley 23 Driven Pulley 25 Belt 30a 1st bearing 30b 2nd bearing 31a, 31b Outer ring 33a, 33b Inner ring 35a, 35b Rolling element 36a, 36b Gris groove 40a, 40b, 41a, 41b, 45, 67c Preload applying member 65a, 65b Ring member 66 Core metal 67a Elastic body for outer peripheral seal 67b High load absorber 67d Elastic body for inner circumference seal 80 Electric power steering device 100 Housing 101 1st main body 103 2nd main body 105 3rd main body AX Central axis CN virtual line CNa, CNb reference line LC1, LC2, LC3, LC4 Extension of contact angle

Claims (13)

ハウジングと、
前記ハウジングに収容されるナット、前記ナットを貫通するねじ軸、及び前記ナットと前記ねじ軸との間に配置される複数のボールを有するボールねじ装置と、
動力源から動力が伝達されて駆動する駆動プーリ、前記ナットに固定される従動プーリ、及び駆動プーリと前記従動プーリの外周面に巻き掛けられるベルトを有するプーリ装置と、
前記ハウジングと前記ナットとの間に設けられ、前記ナットの中心軸に平行な中心軸方向に並ぶ第１軸受及び第２軸受と、
前記第１軸受及び前記第２軸受に予圧を与える予圧付与部材と、
を備え、
前記第１軸受及び前記第２軸受は、正面組合せに配置されるとともに、前記従動プーリの両側にそれぞれ配置され、
前記第１軸受及び前記第２軸受のそれぞれは、前記ハウジングに嵌め合わされる外輪を含み、
前記外輪は、前記予圧付与部材によって前記従動プーリに向かって押圧されるとともに、前記従動プーリと離隔して前記従動プーリとの間に隙間が形成されている
動力伝達装置。 With the housing
A ball screw device having a nut housed in the housing, a screw shaft penetrating the nut, and a plurality of balls arranged between the nut and the screw shaft.
A pulley device having a drive pulley that is driven by transmitting power from a power source, a driven pulley fixed to the nut, and a belt wound around the drive pulley and the outer peripheral surface of the driven pulley.
A first bearing and a second bearing provided between the housing and the nut and arranged in the direction of the central axis parallel to the central axis of the nut.
A preload applying member that preloads the first bearing and the second bearing, and
With
The first bearing and the second bearing are arranged in a front combination and are arranged on both sides of the driven pulley.
Each of the first bearing and the second bearing includes an outer ring fitted to the housing.
A power transmission device in which the outer ring is pressed toward the driven pulley by the preload applying member, and a gap is formed between the outer ring and the driven pulley so as to be separated from the driven pulley. 前記第１軸受の接触角の延長線と前記ナットの中心軸とが交わる第１交点と、前記第２軸受の接触角の延長線と前記ナットの中心軸とが交わる第２交点と、は前記ナットの中心軸上で一致し、
前記従動プーリの外周面の前記中心軸方向の中央を通り、かつ前記ナットの中心軸と直交する仮想線は、前記第１交点と前記第２交点の両方を通る
請求項１に記載の動力伝達装置。 The first intersection where the extension line of the contact angle of the first bearing and the central axis of the nut intersect, and the second intersection where the extension line of the contact angle of the second bearing and the central axis of the nut intersect are described above. Match on the central axis of the nut,
The power transmission according to claim 1, wherein a virtual line passing through the center of the outer peripheral surface of the driven pulley in the central axis direction and orthogonal to the central axis of the nut passes through both the first intersection and the second intersection. apparatus. 前記ナットの外周面には、硬化処理されて転動体が転動する内輪軌道面が２つ形成されている
請求項１又は請求項２に記載の動力伝達装置。 The power transmission device according to claim 1 or 2, wherein two inner ring raceway surfaces are formed on the outer peripheral surface of the nut so that the rolling element rolls after being hardened. 前記ナットの外周面には、径方向内側に窪む溝部が形成され、
前記従動プーリは、樹脂製であり、インサート成型により前記ナットと一体化され、
前記従動プーリは、一部が前記溝部に入り込んでいる
請求項１又は請求項２に記載の動力伝達装置。 A groove that is recessed inward in the radial direction is formed on the outer peripheral surface of the nut.
The driven pulley is made of resin and is integrated with the nut by insert molding.
The power transmission device according to claim 1 or 2, wherein the driven pulley is partially inserted into the groove. 前記外輪の外周面と前記ハウジングの間には、弾性部材が介在している
請求項１から請求項４のいずれか１項に記載の動力伝達装置。 The power transmission device according to any one of claims 1 to 4, wherein an elastic member is interposed between the outer peripheral surface of the outer ring and the housing. 前記従動プーリにおいて前記外輪の端面と対向する側面には、凹部が形成され、
前記外輪には、前記凹部内に向かって延出する延出部が形成され、
前記延出部の端部は、前記凹部内に入り込み、
前記延出部の端部と前記凹部との間は、微小隙間によるラビリンス構造となっている
請求項１から請求項５のいずれか１項に記載の動力伝達装置。 A recess is formed on the side surface of the driven pulley facing the end surface of the outer ring.
The outer ring is formed with an extending portion that extends toward the inside of the recess.
The end of the extending portion enters the recess and
The power transmission device according to any one of claims 1 to 5, wherein a labyrinth structure is formed between the end of the extending portion and the recess. 前記外輪に固定されるとともに、前記従動プーリの側面に向かって延出し、前記外輪と前記従動プーリとの隙間を閉塞するシールド部材を備え、
前記従動プーリにおいて前記外輪の端面と対向する側面には、凹部が形成され、
前記シールド部材の端部は、前記凹部内に入り込み、
前記シールド部材の端部と前記凹部との間は、微小隙間によるラビリンス構造となっている
請求項１から請求項６のいずれか１項に記載の動力伝達装置。 A shield member that is fixed to the outer ring and extends toward the side surface of the driven pulley to close the gap between the outer ring and the driven pulley is provided.
A recess is formed on the side surface of the driven pulley facing the end surface of the outer ring.
The end of the shield member enters the recess and
The power transmission device according to any one of claims 1 to 6, wherein the end portion of the shield member and the recess have a labyrinth structure with a minute gap. 前記凹部内には、グリスが充填されている
請求項６又は請求項７に記載の動力伝達装置。 The power transmission device according to claim 6 or 7, wherein the recess is filled with grease. 前記外輪における前記予圧付与部材側を向く端部には、前記ナットの外周面に摺接する第１シール部材が設けられている
請求項１から請求項８のいずれか１項に記載の動力伝達装置。 The power transmission device according to any one of claims 1 to 8, wherein a first seal member that is in sliding contact with the outer peripheral surface of the nut is provided at an end of the outer ring facing the preload applying member side. .. 前記第１シール部材は、
前記外輪の端部に固定される芯金と、
前記芯金に支持される内周シール用弾性体と、
を有し、
前記芯金は、前記外輪の外周面に嵌合する筒状の外周嵌合部を有し、
前記外輪の外周面には、径方向内側に窪み、前記外周嵌合部を収容する凹部が形成されている
請求項９に記載の動力伝達装置。 The first seal member is
The core metal fixed to the end of the outer ring and
An elastic body for inner circumference sealing supported by the core metal,
Have,
The core metal has a tubular outer peripheral fitting portion that fits on the outer peripheral surface of the outer ring.
The power transmission device according to claim 9, wherein the outer peripheral surface of the outer ring is formed with a recess inward in the radial direction and a recess for accommodating the outer peripheral fitting portion. 前記外輪の外周面と前記ハウジングの内周面との間を閉塞する外周シール用弾性体を備え、
前記外周シール用弾性体は、前記外周嵌合部の外周面に固定されて前記ハウジングの内周面に摺接する
請求項１０に記載の動力伝達装置。 An elastic body for outer peripheral sealing that closes between the outer peripheral surface of the outer ring and the inner peripheral surface of the housing is provided.
The power transmission device according to claim 10, wherein the elastic body for outer peripheral sealing is fixed to the outer peripheral surface of the outer peripheral fitting portion and is in sliding contact with the inner peripheral surface of the housing. 前記予圧付与部材と前記外輪との間に介在して、前記中心軸方向の高負荷を吸収する高負荷吸収部を備え、
前記予圧付与部材は、前記中心軸方向で切った断面積が前記高負荷吸収部よりも小さく、
前記予圧付与部材と前記高負荷吸収部は、前記芯金に支持されている
請求項１０又は請求項１１に記載の動力伝達装置。 A high load absorbing portion that absorbs a high load in the central axis direction is provided between the preload applying member and the outer ring.
The preload applying member has a cross-sectional area cut in the central axis direction smaller than that of the high load absorbing portion.
The power transmission device according to claim 10 or 11, wherein the preload applying member and the high load absorbing portion are supported by the core metal. 前記第１軸受又は前記第２軸受の外輪における前記従動プーリ側を向く端部には、前記ナットの外周面に摺接する第２シール部材が設けられている
請求項１から請求項１２のいずれか１項に記載の動力伝達装置。 Any of claims 1 to 12, wherein a second seal member that is in sliding contact with the outer peripheral surface of the nut is provided at an end portion of the outer ring of the first bearing or the second bearing that faces the driven pulley side. The power transmission device according to item 1.
JP2019202770A 2019-11-07 2019-11-07 Power transmission device Pending JP2021076178A (en)

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CN202080075351.2A CN114641632A (en) 2019-11-07 2020-10-22 Power transmission device
US17/774,629 US20220371651A1 (en) 2019-11-07 2020-10-22 Power transmission device
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